imax b6ac covers the bases for most people.
turnigy lipos are also great.

you may wish to invest in a proper mosfet though.

Did you get it from eBay? I saw those there.

Good point by Kbarlow: I suppose I failed to consider that some people may be charging JUST airsoft batteries.... I use my charger for countless batteries (airsoft, RC, camera, even automotive!) so that makes it easier to justify the expense.
"Buy the best you can afford" I suppose would be the most applicable advice here :)

http://www.hobbyking.com/hobbyking/s..._GENUINE_.html
http://www.hobbyking.com/hobbyking/s...ower_COPY_.htm

http://www.hobbyking.com/hobbyking/s...SortOrder=desc
http://www.hobbyking.com/hobbyking/s...s-Airsoft.html

you WILL need a mosfet, not that inline crap, a properly hardwired unit.

Why will I 'need' a MOSFET, aside from the deep drain warning indicator?

You will eventually fry your switch assembly.

http://youtu.be/8M1q1yJfHJo
http://youtu.be/bk9RBub8OpU

Just a word of help if still needed. I bought 2, 7.4 LiPo's and a charger from a local store. 1st battery charged fine, second battery didnt even read in the charger. Tried the other battery to see if my charger died. The end result... 1 battery new out of the case was toast. When I took my charger to the store to make sure before I leave it will charge again. The charger died on me. Soo getting it local saved me what would have been 2 different shipping headaches and a whole ton of trouble. Not to mention a lot less playing time. I hope it helps.

mmmmm. vaporized copper.