Mpowerplayer: A Java WebStart MIDlet Player

mpowerplayer is a Java Webstart application that allows Web users to try J2ME applications directly from the Web before they buy, with the security to protect your midlet.

Mpowerplayer also provides a Developer Environment, claiming to be the only cross platform MIDP 2.0 SDK, offering J2ME development for MacOS.

From the site:

The mpowerplayer software developer kit includes the mpowerplayer as a standalone application. It's a pure Java emulator implementing MIDP 2.0 and MMAPI, suitable for integration with your favorite environment and IDE. Third-party integration efforts exist for Ant, Eclipse, Idea, and we hear of more efforts almost daily.

mpowerplay also provides a catalogue in their demo platform, so you can use them as a distibution channel also...

I actually found it at the Download Page for GMaps, a free J2ME application that displays Google Maps, Yahoo! Maps, Windows Live Local (MSN Virtual Earth) and Ask.com Maps and satellite imagery on Java J2ME-enabled mobile phones, PDAs and other devices.