Data can speak French, apparently fluently, and surely can speak other ancient languagues equally well. I would imagine that he can also speak Klingon well.
I recall that in Nemesis, Data struggles with the Romulan language. Romulans keep themselves away from the Federation, though, so this isn't surprising. What of the other common species, though? Should Data be reasonably expected to know (and be fluent in) Ferengi, Cardassian, Bajoran, Vulcan, Andorian, and the like?
Also, what about Breen? Could Data learn it and communicate with members of the species?
Does anything in Star Trek speak to this?