Batteries for hobby servos?

Currently I'm using Hitec hs 311 hobby servo (I may change to a higher torque rated servo though) & have been running by test rig via bench pwer supply.

I would like to use a rechargabe battery, preferably rechargable via mini USB & as small as possible for weight considerations. What kind of options do I have?

Your options are largely defined by how much current the gizmo (mostly, the servos) will draw on average, and the desired run time of a battery operated gizmo.

Run time is very approximately (battery capacity in Ampere hours)/(average gizmo current draw in Amperes).