I used Craigslist for language purposes just once, to find an Italian conversation partner in late 2009. He was a very nice guy, and the exchange, while short-lived, was pleasant and productive.

While writing this review about three years later, in early 2013, I went back and checked again to see whether one could still use the site for this purpose, and it looks as though one can.

Just pick your city, then search on the relevant languages you would like to swap. I added the word “exchange” to the search terms and came up with a few listings—not a ton, but a few.

A caveat: be careful! Always meet in a public place.