Free GM Resource: Google Translate
My HackMaster group's PCs all shared a common language, but when I introduced my new Dwarven PC I didn't know any of that language and my knowledge of any other language wasn't enough to warrant any real interaction with the others. Luckily this problem didn't have to last long, but in the meantime, how do you roleplay an exotic language that doesn't exist?
This is where Google Translate came in real handy. Before my first game I decided to base Dwarven on Icelandic. German came to mind, and I know some German, but I wanted something a bit more exotic. With Google Translate I was able to come up with a few phrases and keywords to assemble a limited vocabulary to use in-game. Google Translate was able to show me the correct pronunciation of the words/phrases as well, but I know I butchered them horribly. The cool thing about screwing up the pronunciation was that nobody knew any better and as long as I screwed up consistently I was good. I wasn't trying to actually speak Icelandic, just Dwarven...which I loosely based off of Icelandic.
An enterprising GM could easily take this a step forward and assign real-world languages to other fantasy racial and even monster languages. Maybe goblins speak a butchered Polish and Bugbears speak a similar-sounding, but distinctly different Lithuanian.
You could really through the players a curve ball by having actual words to pronounce than a string of gibberish that would be difficult to replicate.