One of the oft-neglected concepts in gaming is of the various languages spoken by player characters and monsters. At most, players who roll well for Intelligence write down a few languages out of the list and periodically remember that they have such a thing. This, of course, becomes an issue when the monsters surrender or the players attempt to parlay instead of fighting. Typically, it's handled relatively simply: PCs with the language get to talk with the monsters.
Personally, I like to have a bit more fun with the concept. The one I've run into most is goblin, which is a great stock humanoid type. The way I figure it, goblins are mostly a savage, uncivilized race who break down into small tribes unless actively enslaved by some higher force, like orcs or hobgoblins. This brings us to the question of what goblin language is actually like.
The first thing about goblin is the counting system. There's really no reason for goblins to have a significant counting system; the exact numbers aren't their concern as much as having a rough estimate. So they have words for one and two, which are pretty much universal, and for "some" (which may vary from goblin to goblin) and "many" (which also varies but is bigger than "some"). This is conveniently frustrating for their interrogators, for whom the difference between 5 and 9 goblins may be more significant. I would expect "some" to be based around the goblin's family or fighting unit, depending on the exact context.
Then there are other fun things. Goblins aren't nice folk. The way I figure it, they probably don't have a lot of words for making nice – as the title of this post says, there's no word for "friend." The closest would mean something more like "goblin of my tribe," with a different word for "goblin of another tribe." A human would mostly be referred to by whether they were a threat, or whether the goblin group could defeat them, or whether they were slavers. No concept of allies and alliances exists, and even attempts at diplomacy would involve threats or admission of weakness. Lofty concepts of "fairness," "equality," "justice" would be boiled down to a handful of ideas - "human nonsense" and "weakness."
Goblin language's richness is one that humans would not prefer - the word for what smells good probably includes a rat on a stick. Threats abound, as do vocabulary for hunting, killing, tunnelling and so on. War is present, but as a permanent condition of goblin society. There is no word for "peace" or even "truce." Likewise, what need is there for a distinction between "earn," "find," and "steal"? If goblins are primarily raiders, and secondarily scavengers, there is fundamentally no difference between them.
This is just a sketch; I think I'll write up a more complete (and definitive, possibly with "translations" for effect) article on goblin speech for the miscellany. Has anybody else done any work on this? Or have any input on what a goblin (or orc, or what you like) language should be like?