These days, if you're looking for technology to support collaborative work, you have a lot of options. Actually, probably too many.
Dropbox. Trello. Yammer. Sharepoint. Central Desktop. Google Apps.
Which one should you use?
Small Business Computing to the rescue!
They've identified the top tools for people-centric collaboration, task-centric collaboration, and file-centric collaboration.
Don't get me wrong - it's not some sort of "this is the tool for you!" magic - but it should help clear up confusion and help you narrow your options, based on what you're trying to accomplish.