Wow, the link to http://www.ec2instances.info/ alone is so helpful. I wish I'd had this set of resources a year ago when I spent weeks trying to understand AWS' own documentation.
If you want to answer the question "What's the cheapest way to get 16gb of ram and 4 cores?" (or the same for a 1 year term) then having a list you can filter and sort is much more helpful than Amazon's pricing pages.
Upvoted for this link alone. I am so, so tired of the scroll, squint, hunt & jump I have to do on the current Amazon EC2 pricing page to compare costs and features of instances. Especially when trying to compare legacy instances (which we still have a lot of) to newer or VPC ones.