I'd recommend Peter Thomas Roth AHA/BHA Acne Clearing Gel, I think it works pretty well on preventing my occasional acne, plus it's not drying my skin out.
Give a try!
one of my friends really recommends a sulphur mask too. I quite like using the origins clear improvement charcoal mask as an overnight spot treatment, though as a mask it works well to clear things up too. (Though I wouldn't recommend using it all over if you have dry skin, unless you follow it up with a hydrating mask or something)