http://www.glottopedia.org/

http://www.unilang.org

http://www.glottopedia.org/This one is under development and doesn't have many articles yet. I guess we'll have to write some. :)
http://www.unilang.orgThis one is pretty nice, thanks! It's the first place I've found comprehensive information on Gaelic.

http://www.bbc.co.uk/languages/