Here are some links to good wireless resources on the web. Feel free to mail the FAQ Maintainer to have others added.

Developers Sites
WapForum - The authoritative source on WAP environment specifications
Wireless Developer Network - Very good collection of resources and information
(Also check Manufacturer Sites)

Articles
Luca Passani's WAP and ASP articles
Luca Passani's WML/XML/ASP articles

Books
The current WAP "bible" - Professional WAP from Wrox

Mailing lists
The Yahoo (prev eGroups) WML and WMLScript Programmers List

Manufacturer Sites
Nokia's WAP Developer Forum
Ericsson's mobilityworld
Openwave Developer's Program

Misc Sites
WapRing (Excellent catalogue of WAP services for both users and developers)
PPT WAP Resource center (Lots of info and links)
dmoz' Mobile Computing:Wireless Data:WAP links
The WML and WMLScript Programmers List Links Vault