E-Commerce Service

Yahoo Small Business

You'd be surprised at some of the sophisticated things being done with the simple e-commerce service at Yahoo Small Business. Yahoo provides everything from templates and wizards to credit-card processing and sales-tax collection. If you sell less than 50,000 units, this is definitely one of the easiest and quickest ways to go online. Even better: A small army of third-party developers stands ready to create Web designs that work specifically with the service. ($40/month and up, plus transaction fees)

E-Mail

Thunderbird

If you have Microsoft Office, you already have Outlook, the industry-standard e-mail app. But if you're looking to save a buck and still get most of Outlook's features, Thunderbird is a capable, free alternative. Message tagging and a speedy, integratedsearch system actually offer a few improvements over off-the-rack Outlook. (free)

Yahoo Zimbra Desktop

Another interesting, non-Outlook e-mail option is Zimbra Desktop, which Yahoo acquired earlier this year. In simple terms, the Zimbra Desktop is an offline version of Zimbra's capable Web-based e-mail manager. It includes everything a small-business user needs: a contact manager, an impressive calendar, a to-do list, and even a simple, integrated document manager for quick note-taking. (free)

E-Mail Marketing

Topica

Don't call it spam: Communicating via e-mail with your customers is cool, as long as they opt in. Topica has been in the e-mail marketing/mailing-list game for years, and most spam filters are pretty kind to messages that are sent through its service. Topica is also one of the most affordable of such e-mail marketing platforms that you can find on the Web--and it sure beats running a mailing list server yourself. ($50 per month and up depending on e-mail volume)

Instant Messaging

Pidgin

You don't have to run four different instant-messaging applications just to communicate with your clients and with everyone in your office. Multiprotocol software like Pidgin allows you to communicate with users across more than a dozen IM services: Not just AIM, ICQ, and other biggies, but also lesser-known ones like Gadu-Gadu (it's Polish) and Zephyr. Trillian is similar, but it supports fewer services. (free)