A123 packs
 

Are they better than nimh? And the charger, does it hook up to a wall outlet?
Which would be better for a Brushless E-maxx?
What packs would work on a brushless E-maxx(planning to put a MMM esc in it)?

I've got some and prefer them to nimh. The charger runs on 12V DC, so you have to either get a DC power supply, or you can charge it off your car's battery.

For an E-maxx, you can get two 2s2p packs, but they won't fit in the battery trays, so you'll have to get a little creative to hold them in.

Ah nvm about the A123s I'll stick to nimh for now..