One of my favourite thing about the works of Tolkien is the depth of lore that went into constructing his fictional languages. Sadly (for me) fictional languages (or at least reference to them) seem to be largely ignored in many of the modern RPGs of late.
Now I'm not necessarily advocating Obsidian construct an entirely new language/languages (I assume that's expensive), all I want is reference to other languages being part of the lore, occasionally being mentioned during the game and perhaps even being a part of gameplay.
E.g. A thing that bothered me about the Dragon Age games was that the languages of the other nation states was barely touched on. Yes, we had Qunari (that was good) and a few elven phrases here and there but the languages of the other countries was neither mentioned nor acknowledged.
Another thing often ignored of late is the use of language as a skill. Look back to Daggerfall where the player could learn orcish, nymph, elvish, giantish, harpy etc. Now in modern TES games the language gap isn't even mentioned.
Also aphabets. Alphabets are cool.