I think one of these is a smart investment. I have one (Powerex MH-9000) that handles as many as four batteries individually, and charges, refreshes and analyzes, breaks in, discharges and cycles. It forms new batteries for maximum performance, gives detailed capacity ratings for matching battery sets, brings back old batteries from the graveyard and restores maximum performance to older batteries. It allows me to match each of these functions with the specific battery capacity.

It only handles AAs and AAAs and wasn't cheap, but with the proliferation of rechargeables has proven invaluable.