Wikipedia is knowledgeable and useful even though it is randomly edited, not considered authoritative and unable to be cited for essays. The articles seem to have developed structure in recent years that allows for easy reference.

Wikis . Some were very well organised for example

http://classroomgoogleearth.wikispaces.com/

Eighteen Interesting Ways and Tips to use GE in the classroom - Google Docs #18 Travel around the world with books

Some Wikis found have been abandoned and need adoption. So the success of a wiki depends on nurturing, enthusiasm and participants and lots of spare moments in time.

However an overdose of virtuality was not providing a collected sound for me. And with relief I am stepping back into reality.