My simple horse race application in AJAX can be found here.

What have I learned from writing this simple application and Microsoft ASP.NET AJAX?  Well, many things...

1) It is not simpler to write a non-AJAX application first and then convert to AJAX later.  Due to the need to place UpdatePanel judiciously, it's much better to start off with an AJAX application.

2) ASP.NET AJAX seems to be unable to handle multiple active AJAX timers on the same page.

3) User control is the way to go even for very simple repeated constructs.  This reduces your code redundancy and makes code more modular.  My simple track + bet + payoff + actual horse move is done as a user control.

4) I should have done more input checking.  However, given this is fake money with no real consequence, I just did the simplest checks that in no way are meant to be true production proof quality.