Mugen Power, well known for their extended mobile phone batteries, has released a high capacity 1800mAh battery for the Sprint HTC Hero. As far as I’m aware, the Sprint Hero comes with a 1500mAh battery, so this Mugen battery provides a 20 percent boost in capacity.
For those worried about using third party batteries, Mugen has an excellent reputation for reliable batteries. You also don’t need to use a separate battery cover, which means you can keep your Hero looking as thin as it is now. You can find it for $33.95 here with free shipping.