I've been pulling my hair out trying to get a handy ec2 snapshot backup/management working. My google results have ranged from broken libraries to using bash scripts to do one aspect and php scripts to do another, all of the solutions seem to have serious issues with regions.
Anyway I've coded up a very very stupidly simple bash script that's based on the ec2-api-tools. Ubuntu based info here. Essentially sudo apt-get install ec2-api-tools should get the required tools.
What it does: Backs up all instances and deletes all snapshots older than 7 days.
You can find it here, hope it helps.
Due to major problems with ec2-api-tools I've done a quick rewrite for to support euca2ools. Essentially I had this script running on a micro instance and due to bugs with the ubuntu kernel and java it would tank my server so I've switched to the python-based euca2ools.
You can find this script here.
To get euca2ools work simply install via sudo apt-get install euca2ools and add this to ~/.eucarc