Easy as Pie Ajax Requests - Create compelling ajax in minutes with simple examples. | Notes from Phazm
This is a good straightforward hands-on explanation of Ajax: succinct and clear.
Behaviour : Using CSS selectors to apply Javascript behaviours
An excellent alternative to the inline cruft so common in most Ajax applications.
Related links
MiniAjax.com / A showroom of nice looking simple downloadable DHTML and AJAX scripts
A collection of scripts. There might be some good stuff here but use with care and discretion.
Vitamin Features » Go forth and API
Cameron has written a great article on using APIs with Ajax. I love the idea of using .htaccess to fake a proxy and get around the same-site restriction.
The JavaScript Library World Cup [JavaScript & DHTML Tutorials]
Dan Webb does an excellent job of comparing the big four JavaScript libraries that were discussed at @media.
12 perfect cases for Ajax
Yes, Ajax is over-used but here are some cases where it really helps.
Related posts
Ajax workshop in NYC
Learn DOM Scripting and Ajax in the Big Apple.