Here is what I use http://www.newegg.com/Product/Produc...82E16875999020

Works great and will even recharge the AA batteries via a USB port. Comes with a tip that works with the 770 which I assume is the same for the N800. Plus there are a bunch of other tips that come with the product for use with other devices, such as cell phones. While it charges the Nokia, it does so very slowly and I find it better used to supplement the on-board battery.