well, next time you get live plants, give em a look over for snails. as for getting rid of, there are some chemical treatments out there, but i'd advise against them. you can always just pick them out as you see them (jsut be careful, i was told, though i don't know if its true so don't take my word on it, but if you crush them, you could end up releasing eggs and creating more snails...............).
what do you have in the tank already and how big is the tank? loaches are great little fish and eat snails, if you have the room and right tankmates you might be able to get a few of the smaller variety loaches (like chain or pygmy loaches, or yo-yo loaches).