I'm looking for something that can copy (preferably only changed) files from a development machine to a staging machine and finally to a set of production machines.
A "what if" mode would be nice as would the capability to "rollback" the last deployment. Database migrations aren't a necessary feature.
UPDATE: A free/low-cost tool would be great, but cost isn't the only concern. A tool that could actually manage deployment from one environment to the next (dev->staging->production instead of from a development machine to each environment) would also be ideal.
The other big nice-to-have is the ability to only copy changed files - some of our older sites contain hundreds of .asp files.