Free Software/Web Tools.

Collaboration & Diagramming Tools (Free)
- DimDim (synchronous white board, chat, PDF upload, etc...) Integrated w/ Moodle!
- Vyew (synchronous whiteboard, chat, PDF upload, etc...)
- Gliffy (asynchronous)
- Mindomo (asynchronous)
- Yugma - Cross platform, screen sharing, free w/ up to 10 people.
- Cmap Tools (Cmaps Server required for synchronous collaboration)
- "OOVOO" Video chat with up to 6 people (like Adobe Connect) simultaniously; FREE.

**I recommend the above tools hands down. See othersh below**
- Thinkature (synchronous)
- Flowchart (synchronous)
- Bubbl (asynchronous) [Not misspelled]
- Mindmeister ( asynchronous)
- CompendiumInstitute (not yet tested)
- WebofWeb (not yet tested / Synchronous)
- Mind-Mappinig.org: Mind Mapping Software and Websites (Loads of them)
-(Want more? See Vic's entry here.)