Our next-door neighbour has an old bath in his back garden that frogs breed in (I think he has a pile of boulders in one end so the frogs can get out. I often get tiny froglets in my garden, and occaisonally the big ones will come in (I think there's one living in the leaf litter of the rowan at the bottom of the garden). They do an excellent job of clearing up the slugs, and something is eating the snails and leaving the shells intact (don't think this will be a frog?), I often find an empty shell under the bird feeder (the shell is entire, so it's not a song thrush).
I quite like the frogs, although one did make me jump when I was clearing some leaves off the patio, it leapt from a pile of leaves, right on to my wellies, then off again. I didn't have time to scream, but it took ages for my heart rate to go down again!