covaithe
Explorer
We're perennially short on leaders and controllers. I don't have exact numbers to hand at the moment, but I think clerics are the least represented class. Well, except for swordmage; but they're relatively newly allowed, and there are lots of other defenders.
As for races, I don't know that there are any particularly in demand. We allow MM races, so we have a wide variety of races in play. Off the top of my head, the only races represented by more than one or two characters are humans, dwarves, elves, and maybe eladrin. Humans are way out in the lead. There are a handful of races with no characters at all (orc, goblin, githzerai, shadar-kai... probably more), but that's not really a problem. Make whatever race you like.
As for races, I don't know that there are any particularly in demand. We allow MM races, so we have a wide variety of races in play. Off the top of my head, the only races represented by more than one or two characters are humans, dwarves, elves, and maybe eladrin. Humans are way out in the lead. There are a handful of races with no characters at all (orc, goblin, githzerai, shadar-kai... probably more), but that's not really a problem. Make whatever race you like.