7 Reasons Why Web Apps Fail

Some good points to keep in mind when developing your apps.
7 Reasons Why Web Apps Fail

60 More AJAX Tutorials

A great list of AJAX tutorials, from the same guy that brought us the list of 50 AJAX frameworks.
Max Kiesler - 60 More AJAX Tutorials

Field validation with Prototype * Dexagogo

Nice field validation technique.
Really easy field validation with Prototype * Dexagogo

Rocky Shoals of Ajax Development

Resource for quirks and problems one might find when implementing AJAX techniques.
Alex Rocky Shoals of Ajax Development

50 AJAX Toolkits and Frameworks

A good listing of AJAX toolkits and frameworks. In addition to the 50 in the list, there are also many additional ones listed in the comments section of the featured site.
Round-up of 50 AJAX Toolkits and Frameworks