My vote for best case is the Neodigits 5700mah battery-wallet case. No belt clip, but there's a 5700mah battery in the case.... here for $119:
http://cgi.ebay.com/ws/eBayISAPI.dll... 441&tc=photo
or from Neodigits directly for $129. thay ship FAST, too, and take paypal....
I also alternate between this case and a cases.com horizontal smooth black leather case (45$) with Mugen 4500mah battery--yes, the attached Mugen fits in the case!
-Jonathan/jmirabil [jonathan_mirabile@hotmail.com]
p.s. I'd not recommend using these batteries of you've upgraded to ROM 1.10 or are running ROM 1.10.. there can be some issues if so.... But on an non-upgraded 1.00 rom hx4700, you get like 10 hrs with BT+WiFi on, and 15hr+ otherwise... and you get a cool mini-wallet and usb charge cable (Free) with the neodigits 5700mah one. Only downside--cannot charge the neodigits-enabled hx4700 in the cradle....need a USB cable (and a LONG charge time) or the ac adapter with the ipaq connector adapter.