One of the things I've been meaning to get around to is programming a Twitter client for Palm. I haven't got the time or energy or expertise to write a full application in C or equivalent. 
So I started experimenting with Rexx, a free scripting language that can be interpreted interactively on the Palm Pilot.
It's quite hacky, and definitely not what you'd code something important in. But what's nice about it is that you can download it and start playing with it on the Palm Pilot itself.
I managed to start sending HTTP GET and POST requests very quickly. One could easily produce simple 'geeklets' (widgets but without the fancy graphics) that execute in the Rexx environment. So, a little mini application to post to Twitter would be relatively easy to build. In fact, anything that just POSTs or GETs data from an HTTP server (or any kind of server, tbh) might be pretty easy to develop in Rexx.
There's lots of other cool projects that one can do on the Palm platfor. There seems to be a good selection of open source, and a few different programming languages.
Perhaps we should try some wacky ideas like making a program on a Palm Pilot, compiling it on there (OnBoardC) and then distribute it by beaming it to other Palm users only. 
If you are interested in the future of the Palm platform, I'd suggest reading TamsPalm. It's a great blog and covers a lot of interesting stuff about the platform. If this doesn't interest you, I'm sure there's some invite-only Web 2.0 application that will. Consider yourself mildly snarked.
I'm glad to see that some folks are even working on porting Linux to the Palm platform. According to Alexander at Tams, the TX is supported but they haven't gotten the Linux port to go online over wi-fi or Bluetooth.
