This list is from here: 101 Useful Resources for Online Entrepreneurs, but I have removed all the links that aren't free and republished. I will also add more as I find them. It is a terrific list of resources for the those starting or operating business. As I read through the list, it was difficult to figure out from the descriptions which ones were free, so I edited the list and crossed out the ones that aren't. Enjoy. Please visit the original link above as well, as I would hate to be accused of link jacking... just wanted to make the list more usable and it was a real pain to sort through them all - trying to save you the trouble.

Communications/VOIP

1. Skype - Free calls over the internet to other people on Skype for as long as you like.
2. Vonage - Leading provider of VoIP internet broadband telephone services.
3. Gizmo - Low cost international calling and free calls to users on Yahoo Messenger, Google Talk, Windows Live users and SIP networks.
4. Vonics Digital - Plans start at $12.99 per month lowest price available in the market.
5. VoipBuster - Free program that uses the latest technology to bring free and high-quality voice communications to people all over the world.

Data Backup

1. Mozy - Industry-leading solution for online backup.
2. Intronis - Online backup solution with remote computer data backup software.
3. Carbonite - Unlimited online backup for one flat fee.
4. Data Deposit Box - Your source for online backup, and secure online data backup.
5. Athena Backup - Automatically backup your home computer files with Athena Backup.
6. Data Protection Services - Secure online backup services, free trial!

1. I couldn't find any of these for free... But GDrive works pretty well and also - which is not to be confused with the GDrive project from Google, which will blow most of these out of the water.
2. Micro$oft SkyDrive looks promising too.

Invoicing

1. Bamboo Invoice - Simple, Open Source, Online Invoicing.
2. FreshBooks - Online invoicing and time tracking service. - Limited number for free
3. Transcepta - Electronic invoicing solution.
4. Blinksale - The easiest way to send invoices online. - Free, but you only get three invoices per month in that version
5. InterlinQ Solutions - Providing a daily job report, time sheets, job tracking, construction reports and mobile billing.
6. Bill My Clients - Easy way to create and send invoices and bills to your clients. - Not free, but reasonable considering they actually send by postal mail.
7. Billing Orchard - Online electronic billing software application.
8. 2nd Site - Secure invoicing service w/ online invoice payment & online employee timesheets. - 3 Invoices per month for free

Financial Management and Accounting

1. Intacct - Delivers ERP software as a service to small and midsize companies.
2. QuickBooks Online - Accounting Solutions for professionals and businesses.
3. Xero - Slash the hours you spend every week on accounting administration. - Can try for free, but have to pay to setup a live company

Time Management and Project Management

1. Google Calendar - Free online shareable calendar service.
2. Vitalist - Web based task manager designed to work with Getting Things Done (GTD). - Free to 10 projects
3. Backpack - Personal and small business information management, intranet, and to do list organizer. - Free for 2 users
4. Basecamp - Web-based tool that lets you manage and track projects. - Free for 1 project
5. Goplan - Online project management app. - Free for 2 projects
6. Copper Project - Project Management Software.
7. Side Job Track - Web-based job tracking, invoicing, reporting & project management software.

Contact Manager

1. Big Contacts - Web Based Contact Manager for 2 to 2000 People. - Free to 100 contacts
2. Highrise - Shared contact manager. - Free for 2 users
3. BatchBook - Easy-to-use contact management system. - 1 user - 200 contacts
4. Relenta CRM - Small business CRM software. - 1user - 250 contacts
5. Oprius - Sales and Contact Management Software for Independent Sales Consultants.
6. PipelineDeals - CRM made simple - $15/User/Month. - Says it's free, but I think it actually will cancel after 30 days.

Hiring Freelancers

1. Elance - Outsourcing to Freelancers. - Post for Free
2. Guru - Free service helps you find freelancers, get free quotes, and get your project done.
3. SmarterWork - Top small business services marketplace. -
4. Contracted Work - Work Jobs Freelance Search.
5. oDesk - Global service marketplace for small and medium sized businesses.
6. Get A Freelancer - Freelance programmers and web designers.
7. BizReef - Online Services platform.

Online Reputation Management Tools

1. claimID - Free, easy way to manage your online identity.
2. Google Alerts - Email updates of the latest relevant Google results.
3. Yahoo Alerts - Free, personalized notification service.
4. Technorati - Real-time search for user-generated media.
5. FindMeOn - Manage your circles of friends, family, colleagues and others.
6. myOpenID - Secure OpenID provider.

Accepting Payment

1. PayPal - World renowned.
2. Google Checkout - Google’s way to send and receive money.
3. Neteller - Online payment solutions.
4. Moneybookers - Cheaper way to send and receive money worldwide.
5. iKobo - Pick up your money at over 1000000 Visa ATMs.
6. CheckFree - Provides financial electronic commerce services.

Shopping Carts

1. Zen Cart - Free, user-friendly, open source shopping cart system.
2. osCommerce - Free online shop program.
3. AgoraCart - Free shopping cart.
4. OpenCart - Open source PHP-based online shopping cart system.
5. Ubercart - Open source e-commerce suite.
6. X-Cart - Shopping cart software & PHP ecommerce solutions.
7. NetSuite - Integrated web-based business software suite.
8. ZNode - ASP.NET shopping cart.
9. Fortune3 - Ecommerce Shopping cart software.
10. Network Solutions - Robust, customizable Ecommerce online shopping cart software.
11. Kick Start Cart - Business professionally over the Internet.
12. Secure Delivery - The best digital download management site on the net! - Free for 1 product

Social Networking

1. PartnerUp - Find business partners, opportunities to get involved in businesses.
2. Cofoundr - Cofoundr is a private community for entrepreneurs.
3. Fast Pitch Networking - Business Networking Social Network for Business Professionals.
4. Killer Startups - Reviewing new startups.
5. Konnects - Business technology focus groups and networking events.
6. LinkedIn - Strengthens and extends your existing network of trusted contacts.
7. Ryze - Business Networking.
8. StartupNation - Provides real-world business advice to people who want to start a business.
9. Startupping - Community resource created for Internet entrepreneurs.
10. UpSpring - Business networking.
11. Ziggs - White pages and free people search for professionals.

Finding Funding

1. GoBigNetwork - Angel investor network/venture capital.
3. Find That Money - Formidable presence in consumer finance. - Free for very limited trial
4. Venture Deal - Venture capital database.
5. American Capital Advance - Fast Business Loans.
6. Financing: Where to Find It

CPC Revenue - Many in the CPC and CPM section are based on your site traffic volume, etc... but after signup and approval, they all seem to be free from the content publisher standpoint.

1. Google AdSense - Google’s CPC Network.
2. Yahoo! Publisher Network - Yahoo’s CPC Network.
3. ABC Search - Get paid per click by ABC.
4. AdBrite - Webmasters can buy and sell text ads based on their site’s topic area.
5. Chitika - The leading merchandising network for bloggers.
6. Bidvertiser - Pay per click advertising.
7. Kanoodle - Distributes results to a large network of other search engines and search box providers.
8. Clicksor - Effective online advertising technology.
9. Kontera - Advertiser and Publisher Solutions.

CPM Revenue

1. ADSDAQ - A new advertising exchange.
2. ValueClick Media - One of the largest and most effective online advertising networks.
3. AdDynamix - Full-spectrum interactive provider delivering ad management.
4. Morning Falls - Online advertising solutions to advertisers and publishers worldwide.
5. CPX Interactive - Online ad network.
6. BurstMedia - Internet advertising network.
7. Casale Media - World’s fastest growing provider of online media solutions.
8. Tribal Fusion - Focused on high quality sites with targeted content and significant reach.
9. BrightRoll - Video advertising.
10. Adtegrity - Internet Advertising Solutions.