My brother-in-law sells beneficial insects for a living, including the occasional mollusk:
"decolate" snails. They're a small pointed snail that eats the eggs of the pesty kind. I've released them both at my house and at my community garden plot and though I don't see them around often, (they're shy) I think I have fewer of the escargot type. The catch is that it takes them a year or two to get established, and in the meantime you cannot use snail poison of any kind. I'll ask him if they eat slug eggs too.
His main customers are citrus orchards. He's also working on a scheme to collect garden snails, cook and freeze them, and send them to France. Apparently the forests of France and fresh out of snails.