An Introduction to Atmel Microcontrollers
This is a basically a presentation, with audio narration, providing an overview of the wide range of MCUs available from Atmel, including the AVR (8-bit, 16-bit, and 32-bit) and ARM (32-bit) parts, plus a look at some of the development tools available for the AVR and ARM families.
If you're new to the Atmel microcontroller lineup, this is a good place to start. For those already familiar with the family, there's probably not a lot new here, but if it's been awhile since you've looked at these parts, this is a nice overview and a quick Atmel refresher course.
The presentation consists of 31 parts, and takes about 15 minutes to work through.
You can also view a version without the audio narration: here.