Well I keep checking my fish pond, and every time I find toad eggs I toss them. The Frog eggs are allowed to stay. This way I keep SOME toad number down, and I also cull any I find at my home.... I AM doing MY bit!
Not really killing them can have an effect on the local population, sure it wont wipe them out but it does make a small differance. Outside urban areas i would agree that it does practically nothing. I think killing the toads and stopping them from breeding near me has help changed the lawn from being full of baby toads to being full of little frogs.