How to use Wikis
A very informative piece by InformationWeek deals with using wikis in corporate world but the ideas can be applied elsewhere where group work is the name of the game (school projects for example).
The basics
Named after wiki-wiki, the Hawaiian word for quick, wikis are essentially Web pages that anyone — or at least anyone with permission — can create or edit.
What for
Wikis can centralize all types of corporate data, such as spreadsheets, Word documents, PowerPoint slides, PDFs — anything that can be displayed in a browser. They can also embed standard communications media such as e-mail and IM.
thus avoiding the mess of coordinating versions of given files between several team members etc.
Obviously there’s more to read and I highly recommend that you do.