A few thoughts--'cause there's ALWAYS a way to turn this kind of thing to your advantage:
For the natural werewolf: Bring the party to Verbrek (as has been suggested), and see how Alfred Timothy and the rest of the Verbrekers like a lycanthropic "race-traitor" (assuming the werewolf isn't just as evil as they are). Alternately, bring the party to Kartakass and introduce them to some of Harkon Lukas's greater wolfwere friends--I'm sure they'll all have lots to talk about, since werewolves and wolfweres get along so famously.
For the half-dragon: Depending on how comfortable you are with the terrain of Darkon, introduce the party to Azalin--or more specifically to Ebb (and possibly Gloom, if you use the Dread Possibility from the Gazetteer). While I've never dealt directly in-game with a half-dragon, I would think any full dragon (particularly an EVIL full dragon) would see a half-dragon as (at best) a useful servant or (at worst) a weak and pathetic abomination to be exterminated. You know, something along the lines of "you polluted half-breed b*****d." The half-dragon blood might make him/her unusually susceptible to Ebb's commands, operating as if under a continual
charm person spell whenever they're within a mile of each other.
For the "dwelf": There're plenty of possibilities here--bring them to Sithicus and see how antsy the Sithican elves get when they see some creature that has recognizable elvish blood but distinctly dwarven features as well. Or, depending on how freaky this character looks, bring them north to the Sleeping Beast mountains in Lamordia, where it's rumored a battered dwarven city still ekes out a meager existence--I think the Mordent Cartographic Society's maps call it Mitternacht or Dunkelheit. Despite the chilly air, I'm sure they'd get a "warm" reception.
Alternately, bring them into the main "demi-human haters" domains, such as Falkovnia (where all non-humans are state property), Lamordia (where no one believes in that foolishness anyway), or the Shadow Rift (where they can meet Gwydion, who pretty much hates everything).
I know these ideas may seem heavy-handed, but if they're real power-gamers they may actually enjoy it. Of course, being a power-gamer/munchkin/etc. brings with it its own problems--and if they're powerful enough to wade through most "garden-variety" Ravenloft threats, bring out the big guns, shoot at the PCs' feet, and watch them dance.
I've offered these suggestions under the assumption that the players are doing this primarily to irritate you as the DM, and to generally be annoying. If they're simply players who've seen it all and done it all before and just want a new roleplaying experience (and are willing to work in partnership with you as the DM to make that experience better), then it's a different situation. My DM has been gaming (in Ravenloft, the Forgotten Realms, Spelljammer, Dragonlance and Greyhawk) for about 15 years now, so I typically don't blink when he creates a female sea-spirit-folk Oriental monk/ranger/druid/illusionist natural seawolf lycanthrope with a magical torc that allows her to shapeshift into a Tarrasque.
Um, well, okay, I blink a little.

But everyone has their own limits on what constitutes playable characters and what is simply a detour into the ridiculous.
Anyway, hope these gave you some ideas. When these characters continually get run out of villages by angry mobs (brandishing the requisite torches and/or pitchforks) or attacked by Darklords (or their most powerful servants), they might start taking steps to conceal their exotic nature. In fact, if at that point you feel charitable enough to throw in a
hat of disguise, you might get to see them fight each other over it.
