JavaGear ME is a highly optimized Sega Master System and Game Gear emulator for Java enabled mobile devices. It is based on the original JavaGear, but significant portions are completely rewritten. Compatibility is also higher.

Changes:

Improved Emulation Accuracy:
Fixed interrupt issue where VBLANK could be taken within instructions.
Fixed Back To The Future 2. (Not that you’d ever want to play it.)
Fixed Bonkers Wax Up!
Both games tried to perform an invalid memory read.

Bug Fixes:
Fixed PAL/NTSC bug where mode was not always correctly set.
J2SE: Made this version scale screen by default

Thanks to http://www.aep-emu.de for the news.

http://www.javagear.co.uk/index.php

This release is pretty old but worth to be mentioned. “Lode Runner” is a free and open Source ‘Lode Runner’ game for Mobile Phones (J2ME MIDlet).

Features:

Clone of the original Apple II version Both ‘LodeRunner’ and ‘LoderRunner Championship’ versions are supported (300 levels total)
Source is heavily commented
Tested with Nokia phone MIDP 2.0 (should be easily portable to MIDP 1.0)

http://code.google.com/p/loderunner/

Mobile Trail Explorer is an application where user can view and record tracks using the mobile phone and GPS device. Recorded tracks can be exported in KML or GPX format. KML file can be viewed in Google Earth application. Mobile Trail Explorer is mainly targeted for recording biking, hiking etc. trails.

Software runs on Java platform so it is supported by many mobile phones. It is required that mobile phone supports Bluetooth connections (JSR 82) for GPS and File connection (JSR 75) for exporting trails to kml files.

http://code.google.com/p/mobile-trail-explorer/

JME C64 runs on Java-enabled (MIDP 2.0) mobile devices.

Thanks to http://www.aep-emu.de for the news.

http://sourceforge.net/projects/jmec64

Java GB is a Java-based Gameboy and Gameboy Color emulator for mobile devices. If you want to play Gameboy games on your mobile phone you should try this emulator.

Thanks to http://www.aep-emu.de for the news.

http://sourceforge.net/project/showfiles.php?group_id=219240

GameBoy emulator (not GameBoy Color) for J2ME based on Mario GameBoy (TM) Emulator 0.2.4 by Carlos Hasan with good speed enhancements and many useful options. GPLv2 license.

Thanks to http://www.aep-emu.de for the news.

http://sourceforge.net/projects/cuteboy