I finally got around to actively using Michael Schwarz's Ajax..NET library for XMLHTTP development with ASP.NET.  It's very easy to use (I actually got confused at how easy it was), and if you can get past the return to hard-coding some of the DHTML elements again.

I did a simple series of auto-populating TextBox controls that react dynamically to changes in a main box.  Nothing earth-shattering, just proof-of-concept programming to improve otherwise tedious form completion, and the likes of which I've done previously in pure Ajax, but just with a new take.  I may wind up rewriting an interactive I did for a client registration form based on this library, I'm enjoying working with it so much. 

Bravo, Michael!