Don't know if you want it to be a geektool replacement or if it doesn't matter, but I personally think the yahoo widget looks 100x better then anything you can do with geektool. Heres the link if your interested http://widgets.yahoo.com/widgets/widescapeweather
Just installed it to see if I could get it looking good with my current setup and decided against it. Not saying it doesn't look nice or have a good feture set, just doesn't fit in currently.
I did however find something odd when I installed the YahooWidget Engine. It COMPLETELY REPLACED my iSerial Reader app. Not that I use it much, just very very very odd to see.
I don't think I'll be using Yahoo Widgets again due to this.