I've looked, I can only find one that disables their explosions from doing more than player damage, but I can't find one that turns them off completely. I'm usually happy playing on peaceful but some friends of mine want to turn monsters on, and I'll only do it if I can completely get rid of creepers. It's not just that they destroy my property that I hate about them, it's that they scare the hell out of me. At least you can hear the other mobs coming. Basically just a plugin that keeps creepers from spawning for Bukkit. (The only one I found on Google was for vanilla.)
I think either WorldEdit, Essentials, or WorldGuard can do that. You can look into it more, but you should already have them (They're just that awesome).
I can't get WorldEdit or WorldGuard to work for me for some reason. I tried yesterday to get CommandBook and WorldEdit to work and they wouldn't. The creator has no idea why...
My plugin regios can do this, or as others have suggested there are specialised plugins for this : http://forums.bukkit.org/threads/ad...rmissions-support-tons-of-features-740.15898/