Snails worth it in a small tank?

[BirdOfPray]

When I bought some anacharis for my 5-gallon betta tank, a small snail hitched a ride. So far (a little over a week) there has been no obvious snail population explosion -- just the one little guy scooting around in there. I've let him be for now, because it seems from my research that he'll just eat algae, decaying plant matter, and leftover food that sinks to the bottom (if he gets to it before it starts going bad). I'm still perfecting my technique for cleaning the gravel with water changes on this tank, so I figure that can't hurt. But then I started to wonder if that one small snail really makes much difference. Does it? And if not, are the larger snails sold in pet stores actually beneficial to a tank or just something you get because you like them? Obviously I don't expect any animal to eat rotting food or fish waste, but there's certainly room in the tank if there would be any advantage to having a larger type of snail. I've done some reading online, but some of the information seems to conflict and I'd love to hear from anyone who's actually kept snails.

[Wild Turkey]

For the care involved and price (both virtually none) mts are the best bet if you want to introduce a helpful snail species into the tank, as long as you have the right substrate

[toddnbecka]

A single snail isn't going to have much impact on anything. Provided it arrived before it was sexually mature, there won't be any more. If it did mate (ramshorns and "pond" snails are hermaphroditic) you'll see egg clusters and/or tiny snails sooner or later. They'll only reproduce according to available food, so if you don't overfeed a few won't become a few thousand.
Larger snails are generally kept as pets, the same as fish or other aquatic critters. Some folks love them, personally they don't particularly appeal to me. I do like the assassin snails for controlling the numbers of other species, they're better than using chemicals IMO.