This reminds me — I need some new batteries. A few of mine just died from overcharging.

Adventures in Rechargeable Batteries

For one thing, there’s the issue of discharge rate. It turns out that massive 2500mAh capacity of the Energizer rechargeable battery doesn’t mean much when the battery drains itself within a month.
[…]
So putting a larger number on the box is ultimately a method of fooling consumers with marketing. Where have we seen that before? Oh right, everywhere. Caveat emptor.

The Wikipedia entry on NiMH batteries mentions that the hybrid/pre-charged batteries have an advance that reduces the discharge rate

A new type of nickel-metal hydride battery was introduced in 2005 that reduces self-discharge and, therefore, lengthens shelf life. By using a new separator, manufacturers claim the batteries retain 70 to 85% of their capacity after one year when stored at 20 degrees Celsius (68F). These cells are marketed as “ready-to-use” or “pre-charged” rechargeables. Besides the longer shelf life, they are otherwise similar to normal NiMH batteries of equivalent capacity and can be charged in typical NiMH chargers.

(via Daring Fireball)