Depending on what you're doing, you can definitely save money and get similar service with Linode:
http://journal.dedasys.com/2008/11/24/slicehost-vs-linode
Basically, with Slicehost, you are paying to have 64 bit pointers - without that, the price difference isn't that big.
That's pretty much it! What does it add up to? In general, I can tell you that it's a very small percentage of our expenses (salaries is where our $$ goes)...in a way we can't afford NOT to use these tools.