I just watched a very cool web cast for SubSonic (aka ASP.NET ActionPack).  Inspired by Ruby on Rails, it delivers to ASP.NET some of the same features such as rapid prototyping and data scaffolding.  Here's a quote from the SubSonic Community site:

This is our first step to try and pull the fun that Ruby On Rails is back into .NET. ASP.NET is getting bogged down with sooooo much ... "bloat" that it's hard to do our work on a daily basis without feeling like our code is not "best practice". We got into this because we thought it was fun - let's make it that way again!

Add the assembly, update your web.config, add a couple files, and away you go.  Out of the box it supports SQL 2K/2K5, MySQL, and the EnterpriseLibrary.  SubSonic also includes built-in code generators for your apps that must live in a Medium Trust environment.  Definitely worth a closer look.