If you want the tube style battery, then the eGo One battery is an excellent choice. Would fit very nicely with the Nautilus Mini and super compact. The battery is available both in 1100 mah and 2200 mah. No settings to worry about, it is basically a mech mod, but with protection built into it. The power that it will put out will be dependent on the resistance of the coil. Of course, like a mech mod, once the battery starts getting drained, the power will drop. The smaller battery is about the size of a tube of lipstick and the larger battery is about the size of a cigar.
Aspire makes a bunch of tube style batteries as well (the Subohm, etc.) and they even make a VV model. I picked up a subohm one for around $30 just to play around with.