online encyclopedias

[gusl]

I just wrote my first Wikipedia article: Independence-Friendly Logic. I can imagine this being very addictive, watching your article grow, and seeing people do things with it.

Did you know that you can license Wikipedia for your site? Here's an unusual one:
http://www.biologydaily.com/biology/Dialect_continuum

Some online encyclopedias that I know:

Wikipedia
Stanford Encyclopedia of Philosophy (Plato)
PlanetMath