GWeather is a open source J2ME weather forecast application for mobile phones. Uses the Google Weather API. If you like GWeather, you can donate on http://gweather.sf.net/donate.php.
I find this project extremely helpful, it helps me to get an overview of my local weather when i'm on go. but one thing I would like to request to the developer that if you can put auto update feature while application is running(i.e it will update the status after every 5 min or the user defined) then it would be more helpful. Thank You, Rittwick Banerjee