I like snails, they do a good job on the algea control in areas where fish can't reach, and they're great at getting into the crevices and eating all the leftover fish food, an' general waste control.
But if you don't like them for aestic reasons, or that they seem to have multiplied beyond control you can do one of two thing.
1) get a clown loach for your tank if the tank can support it. They love munching on snails and will keep the population in check
2) Tie a piece of raw, rinsed chicken to a string and sink it on the bottom of your tank over night. In the morning, the snails will have collected on the chicken, and you can just rinse them down the drain. Do this for about seven days once a month and your population should be kept in check. Some people say veggies will work on this method as well, but I seem to get better luck with meatier foods.
or you can *crazysmiley* them. Personally, so long as they're not taking over your tank, I'd leave them.
~~Colesea