Shinkansen
Shinkansen, the high-speed railway system of Japan, is a WebForms server control as well as an ASP.NET MVC component which allows you to compress with gzip/deflate, crunch (minify, etc), combine into a single resource, and cache CSS and JavaScript files.
In fact, this very site uses Shinkansen to serve JavaScript and CSS. Go ahead, do View Source.
The latest code, binaries, and documentation are available on CodePlex.
Related blog posts
Mar 28, 2010 Shinkansen for ASP.NET MVC Now Available
Jan 25, 2010 Shinkansen, My New Project, Is Up On CodePlex
Jun 17, 2009 Getting to the Bottom of JavaScript Includes