I'm still kind of new to this myself, but I want to give this a shot: Dual Coil 510 Tank Cartomizer
Looks like a great little tank for a box mod or even an eGo battery (or any other high capacity 510 battery).
I have bought three of these tanks. I would suggest buying the cartos on their site to use with these as the plastic end caps are difficult to use with user punched carts. Two weeks of use on one tank with no leaks and the carto inside has lasted me a week and a half (I vape between 5-7mls a day) so that is alot of life out of a carto for me. Go with the LR version and they rock! And if you have a problem with the carto staying wet give it a few sharp dry pulls to suck juice in.