CodeGuru: CE - Source code and tutorials for topics like controls, database, file handling and memory management. . - http://www.codeguru.com/Cpp/W-P/ce/
The Code Project - Free source code and tutorials covering controls, database, dialogs and windows, and graphics and multimedia. - http://www.codeproject.com/ce/
Windows Mobile Home - The Windows Mobile Developer Center is the starting point for all the information about development for mobile devices provided by Microsoft. - http://msdn.microsoft.com/mobility/windowsmobile/
Pocket PC Developer Network - Resources for developers. Articles, questions and answers, libraries, ActiveX components, books and other information. - http://www.pocketpcdn.com/