I've been using the forecasts on http://weather.gov lately. In fact, using the search field on the left, I entered my zipcode and got taken to a nice forecast page with an obnoxiously long URL that I then bookmarked in Safari and set up as a hotkey in QuickSilver. Now I type Cmd-Space at any time to be taken to a perfect forecast summary with a disgustingly rich set of maps, radar, and satellite images, discussion of the forecast by the forecaster, etc., all a click or two away.
My setup curve was a bit long, but now that it's set up it's unbelievably easy to check the weather. So if you could rig up an app that even approximates that without all the manual setup work that I had to put into it, then I'm sure you'd find hordes of users.
http://www.dreamsongs.com/MFASoftware.html
He draws analogies between software composition and creative writing, performing plays, etc. Worth a look for those interested in the current thread.