Google IM with gmail account
If you have a gmail account, you already have a gmail IM (instant message) account. You may or may not have the other necessary component to work this magic: a Jabber client. I recently set up a Jabber server at work and have been using it for inter-office IM, so I can recommend some free clients:Exodus for Windows
Fire for the Mac
Gaim for Linux
Setting up is easy:
server: talk.google.com
username: yourname@gmail.com
password: yourgmailpassword
enable SSL


Comment posted on 1-14-2006
I should really update this story. I found that Exodus was crashing on occassion on some of our XP clients. I found a much better (stable?) client in Psi. Check that out as well. We’ve been using version 0.9.3, though I see a new version just came out. I have not tried the new release yet.