While ASP runs best, easiest and completely on IIS with NT Server / Windows 2000, there are some products available which allow you to run ASP on other web servers (and even other platforms).
ChiliSoft (
www.chilisoft.com) have several ports for other platorms, including O'Reilly's, Apache and Netscape on NT, and a couple even on Unix.
Stryon (
www.stryon.com) seem to have a pretty decent offering as well, called iASP.
Apache::ASP is a port for Apache that allows you to run ASP (only PerlScript is supported).