Best straight to USB, no battery product?

[CyberSkin]

joyetech ego 1000 mah pass through.

Those are nice becouse you can use it like a battery, take it with you or you can use it like a pass through and only need about 1A to run it. Straight pass though are nice since there are no batteries to wear out and some like the one I use have 5 different voltage setting not including the off. If they made a variable like a twist I would be all over it.