I think Orcs are the easiest of the races to name (next to humans of course). Basically go with sounds that use the back of the throat...Grok, Haagrol, Vok, Morgrom, Vraag, Vrugdok. Klingon names work really well too...Mog, Lursa, Betor (those wouldn't make it through, just using them as an example of the sound you want).
Night Elves are fun to name too. Instead of the boring old elvish style names you see all over fantasy, I prefer Hawaiin words...Pikake, Mahina, Kioke, Kahikole. Those would conceivably be used for Troll names too.