Well, my MIDP efforts paid out. I have sucessfully compiled a midlet using Michael's MIDP kit and the JARs from the Nokia SDK, which proves the original point: you can do Java development for mobile phones in Mac OS X, and many more people would probably do it if the vendors gave their SDKs a little more thought.
I'm still missing a usable emulator (that is, one that can run Nokia's proprietary stuff), and so far I've resorted to using the Linux binaries Nokia provides. It's no big deal to shunt a copy of the JAR across to my Fedora box and invoke the emulator there, but it's just plain stupid not to have a native Mac OS X emulator when pretty much everything else works.
Half an hour later, I had taken apart a number of widgets to see how they worked and started out on a system monitor for my machines. Although the novelty is fast wearing off, I've found Konfabulator to be a very well designed application framework for desktop applets. It is crying out for beefier integration, though - maybe SOAP would help, or a more comprehensive way to invoke shell scripts.
Weather Vanes, Map Vanities
After dropping Konfabulator, I decided to improve on the weather monitor concept and dig out conicplanet, a CGI script that I started using years ago to render an Xplanet-like Earth view with real-time weather overlays. It's a CPU hog, so I hacked it a bit to do some caching and added a near-real-time weather "view" to the site (it's the little map on the rightmost column).
In the process, I discovered OSXplanet, which is overkill for my needs but looks absolutely stunning on my 20" iMac with a couple of very high resolution map images (2048 pixels in width) I had hoarded a few years back: