Seido, one such company, will soon make such a battery available for users of Palm's recent Treo 680 and 750 smartphones. The 1600mAh Seido battery holds 25 percent more power than the 1200 mAH type included by Palm with those devices.

And, unlike many other high-capacity batteries available, this does not change the profile of either the Treo 680 or 750; because it is thin enough not to require a larger battery door.

Available for pre-order now, the new high-capacity battery is expected to ship on July 30th. It sells for $49.99.