There are several good minification tools out there, but we think there are several features that make Rejuicer unique:
Use a simple, readable fluent configuration. Configure all of your minifications inside Global.asax, so that they run once at application start.
Include all files in a directory matching a wildcard (eg ~/Scripts/AdminPages/.js, or ~/Scripts/jquery.js)
Rejuicer integrates into your site as either a HTTP Module or HTTP Handler. It nevers writes to the local filesystem, and therefore runs without issue on cloud providers such as Windows Azure.