I'm really interested in Couchdb, and have probably spent about 20-25 hours on tutorials so far (and probably another 10-20 perusing the Apache couchdb-dev mailing list archives). Honestly, I don't feel comfortable using it on anything serious yet, though I really want to get there eventually. What level of familiarity with CouchDB + indexedDB&webSQL would you suggest is necessary for a potential contributor?
Absolutely none, there have been quite a few contributors without prior experience in the related tech, I mean not all contributors are / need to be programmers, trying to make that easier too.
If you are interested then look around this issues, or get in touch on irc or email and certain to find something that you will be comfortable working on.