There is a new 4000mAh extended battery product designed by Mugen spesifically for LG Nitro HD, which is coming out in May 2012. It is a very indispensable product for those who uses the phone non-stop, who works over the phone, and really require a strong battery capacity. More information can be found here:

[HLI-P930XL] Buy Mugen Power 4000mAh Extended Battery for LG Nitro HD P930 with Battery Door