Elastic IP Address allocation
There's a lot made of the fact that Elastic IP Addresses (EIPAs) are released when an instance stops, dies, or is summarily killed off, but it's not that big a deal. If you're a heavy user, use CloudFormation to launch your instances, and include an EIPA allocation in the launch script. If you're a light (read: hobby or small business) user, create your own Amazon Machine Image (AMI) from a snapshot - it's pretty easy - of an EC2 instance that you've set to assign itself a named EIPA as it starts.
It's good practice to create your own AMIs (with auto-recovery built in) anyway, so that, if/when your EC2 instance terminates for whatever reason, it can be respawned automatically with no human intervention and little loss of service.