Invoicing

Zoho Invoice

Don't need a full-fledged accounting app like QuickBooks? Zoho Invoice is a near-perfect Web-based solution for managing simple billing needs. Create and manage customer accounts, build invoices, and then print or e-mail them with a mouse click. You can also tie in your use of Invoice with Zoho's other, extra-cost business services. See our full review of Zoho Invoice. (free to $35 per month depending on invoice quantity)

Mobile Device Remote Access

SoonR Desktop

It's one thing to be stuck in an airport without access to a critical file back at the office, but what if you don't even have access to a computer? Enter SoonR, which lets you snag files from your PC or Mac via a mobile phone. SoonR isn't built for serious data transfer needs--but it just might get you out of a jam when it counts. (free)

Office Suite

Microsoft Office

Like it or not, any business, big or small, probably needs at least one copy of Microsoft Office somewhere in the building. All of the suite's applications are simply too close to being industry standards to ignore. It can be pricey, but you likely needn't worry about upgrading to the latest version--anything produced since the turn of the century should do. ($85 to $400 per user, depending on version)

OpenOffice.org

Don't want to fork over beaucoup bucks for Office? We can't blame you--and this alternative suite will work for 95 percent of your productivity needs. OpenOffice.org is mostly compatible with Microsoft Office, and operations are similar enough that any Microsoft user should have no trouble using it. The big three apps--word processor, spreadsheet, and presentation tool--are all here, along with a simple database and drawing tool. One caveat: OpenOffice has trouble with Office 2007 files; but the imminent new version, OpenOffice 3, is said to remedy that limitation. (free)

Project Management

Basecamp

Build complicated project timelines, to-do lists, and message boards, and share files among your team members-all via one simple-to-use Web tool. Basecamp can keep all your workers on task while letting everyone else know what other team members are up to. It can even track project time on a per-member basis, for creating detailed billing and reports when the job is done. ($24 to $149 per month, depending on number of projects managed)