• Read and Write Web’s Software for Virtual Teams
• Nick Denton’s (owner of Gawker and Lifehacker) Startup Kit
• Evan Williams’s (founder of blogger.com) list of business web apps
• Added: The Entrepreneur’s Guide to Web 2.0: Top 25 Apps to Grow your Business

In summary, you’ll need these applications the most:

• Email- Gmail is the most popular.
• Calendar to keep track of time- Google Calendar couples with Gmail, both can be used with your domain
• Project Management to keep track of what needs to be done- Basecamp and FogBugz
• VoIP for cheap Internet phone calls. Skype is the most recommended, though Jajah and Gizmo Project seem to be gaining.
• A blog- They’ve recommended Typepad and Blogger, but I still recommend WordPress (there’s also a hosted version)

Related posts:

• Calendars are horrible at Berkeley
• “How we set up a non-profit by the seat of our pants”