i bought a PulseTech Xtreem charger a few months back. it's one of those chargers that's supposed to somewhat de-sulfate the plates by "pulsing" the charge.
it also is good for all types of batteries. i paid around $60.00 for it if i recall.
it seems to work ok. it charged up a dead AMG battery, which really surprised me. that battery had just 0.7v when i hooked it up. it charged up to 13.2v overnight. that didn't last long, as that battery has been sitting for who knows how many years and is junk. however, it's still hovering around 9.8v, even though it is still sitting a couple of months after being charged. i don't know what that really says about the PulseTech charger, but i thought that test was interesting to say the least.