I made a remote control, uses 8 MHz Promini running direct from 3.7V LiPo connected to Vcc line (bypasses regulator).
Keypress creates interrupt, wakes up uC from power down sleep mode, it reads the keypress using the Keypad.h library, sends it out via virtualwire, goes back into powerdown sleep mode.
Uses MAX1811 to charge the battery from a 5V source, like a USB port, but I have a 5V wallwart that powers the receiver, I just move the cord over when I want to charge it. Both have panelmount 5.5/2.1 barrel jacks.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=090-479
or PCB mount if that's your design
http://www.dipmicro.com/store/KLDX-0202-A
wallwarts
http://www.dipmicro.com/store/DCA-0510
http://www.dipmicro.com/store/DCA-0520