Best tip on the page is using CNAME's instead of A records. It's the least obvious of them.

Right. Although it wasn't clear what exactly they meant by using a CNAME. They could have cleared it up greatly by saying using a CNAME to the official DNS name of the elastic IP, i.e. ec2-75-101-137-243.compute-1.amazonaws.com.

You can also use the internal IP address of the machine. i.e. with Windows instances if you do an IP Config you'll see an address to the effect of 10.X.X.X. Instances in the same availability zone can communicate with one another using these IP addresses without leaving the network. This saves dramatically on costs and performance.

Sure, you can do that, but hard coding ephemeral IP addresses into your configuration is still problematic.

On a somewhat unrelated note: there is a very interesting peak on spot history for windows instances on Dec 16th, they jumped up to $200

At some point I need to write a little script that lets you launch with a "shutdown after" somehow. I blew a couple hundred bucks on forgotten machines once. Oops.

I wonder how this applies to things like EngineYard Cloud which provides an IP address using dynamic DNS.

Doesn't impact it. You can still determine the machine's internal DNS name from EC2. Use that (or the RFC1918 IP address).

Good article. Here is a tip to reduce Amazon S3 costs:

http://bit.ly/hn_reduce_s3_costs

:)