Under the topic of "Language Wikis" I include more than one category of item.
There are a number of versions of the Wikipedia in different languages. While this was
not the main purpose of these Wikipedias, the ones in the more obscure languages serve as
good exhibits of some languages for which it may be hard to get samples. Some of the languages
involved are ones that might be considered dialects of better-known languages, and some of
these may even be very hard to find in written form. See this list for a complete list of the
Wikipedias available. (Note that Wikipedia is not very friendly to constructed languages,
and makes it hard to start one in a conlang, so only the very best-known of conlangs are in this
list.)
There are also wikis devoted to documenting the language construction efforts of the past. The
biggest and oldest of these is Langmaker (no link is provided because the home page seems to be
gone; however, many of the individual languages on the site are still online!), but another worth
looking at is the IAL wiki on Wikia.
Finally, there are wikis to help people who may want to help develop a new conlang. By using
the wiki format, collaboration is facilitated. They include The
Conlang Wiki and FrathWiki.
I'm not sure how to categorize this, but the UniLang Wiki seems to be a bit of
each of these, and needs to be mentioned here.
Please inform me of dead links and any
other problems.