YahooGroups has proven absolutely essential for several of the short-term and long-term projects I've managed involving remote staff (all volunteers). Its advantages:
- works on any computer, Mac or PC, and any operating system, including older systems (several of the people I work with remotely work on what most of the TechSoup community would consider ancient machines)
- allows users to choose a variety of ways to view messages (on the web, via email, as a daily digest)
- has plenty of space for users to share files
- has a private chat room associated with each YahooGroup
- allows group users to see who else is online at the same time
- has an easy-to-use search function for the message archive
- has a shared calendar, and also allows users to share their personal calendars with each other
I've also used WebEx twice for remote presentations, and have really liked it -- I'm on a Mac and still use OS 9.x, and it worked just fine.
I've been fooling around with
iVisit, but the remote staff (all volunteers) I work with have been reluctant to try it, or haven't had a good enough Internet connection for such.