The Forum Nokia Wiki is a very powerful site with a lot of good examples. I found some ones very interesting:
How to use the Google Maps API in J2ME mobile devices
http://wiki.forum.nokia.com/index.php/J2ME_Google_Maps_API
http://wiki.forum.nokia.com/index.php/How_to_use_Google_Maps_data_in_mobile_applications
How to use the Sensor API on the Nokia n95
http://wiki.forum.nokia.com/index.php/Sensor_API
UI Frameworks for J2ME
http://wiki.forum.nokia.com/index.php/Java_ME_UI_Frameworks
How to parse XML in J2ME with kXML
http://wiki.forum.nokia.com/index.php/How_to_parse_an_XML_file_in_J2ME_with_kXML
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