Pete made a nice tutorial on the fist steps of designing projects with AVR microcontrollers. He covers choosing the right uC for your project, finding datasheets, getting a programmer/debugger, and setting up the AVRStudio 5.1 for developing and debugging.
In the wee hours of the night, I’ve been continuing to learn how to develop for the various AVR family chips from Atmel. I also do a lot with NETMF, Netduino, and the .NET Gadgeteer, but sometimes (despite the pain!) it feels good to code right on the metal.
Introductory/getting started information for the AVR family is not always the easiest to find, so this post covers a few other important details I think you’ll find helpful.