My favorite asp.net rad tool is the subsonic 2
The reason is simple, its because I know it very well ! every single code of it I know it, and because its open source, and I know it very well, I customize it to my needs, solve very easy anything that comes up, add new future that I need etc.
Subsonic 2 have a Scaffold Code Generator, that is the one you ask for.
a small introducing to this future can be found on this page.
http://dotnetslackers.com/articles/aspnet/IntroductionToSubSonic.aspx
Also if you start working with subsonic 2, and use the scafforld, you can easy make very fast other pages that feet your need, with out the scafforld, but using the same base - the subsonic2 database connection with your data and your database.
So you can combine RAD making page with other custom page and solution to feet your needs using the same tool, using the same knowledge of the tool
Subsonic2 have also other futures, that you can find and use, like the one to be create the database from the struck of your data.
Some more idea you can get here.
http://subsonicproject.com/docs/Main_Page
If you ask me why not with subsonic3, and go with the version 2, the answer for me is because ver3 is new one, and very slow.
So for me you need to get the subsonic2 source code, compile it by your self, make some tests, and start your RAD application...
Now there is a lot of informations for the setup of subsonic2, I know that maybe the first time seems like to go climb up to the mount, then the mount disappear, (at the end the mount is always a mount... zen poem)
Second tool
My second tool that I have use for really rapid application development, is the asp.net maker. http://www.hkvstore.com/aspnetmaker/
I have used it for low budget projects, or where I need for a dirty quick solution, until the final gets ready. What I have did is that I create solution for the easy tables, and make code for the one that need too many thinks to be fix.
The pros is that have many future, its very easy and you do not need to know almost anything to make the interface, create from the database, all the environment that can edit it, have the opportunity to make a lot of adjustments, and what you get is a better page than the Scaffold can product.
The negative is that you stick with what this tool product, and you can not update the pages by your self to make some small changes, because is too complicates one, second if anything change, the pages changes, and even if you rename it and not overwrite it, it maybe not working.
Maybe after a lot of thinking, a tool like that is better in some cases.
You need to test it and see by your self.
Hope all that help you more.
