Long ago I had a Nokia N810 internet tablet, a wonderful device. Developer support was poor, so there wasn't many app choices. Since I was using it mostly as a replacement for my Palm IIIx, I needed a good To-Do application.
The N810 was a Linux minicomputer and there was support for Ruby. To my delight, Ruby on Rails 1.1.2 ran too! I quickly wrote this little web-based application using plain text files as the data backend. Yes, it was overkill; it technically worked, but it was obviously cumbersome. I did use it and it served its purpose until I got an iPhone 3G.
It was quite an achievement, to say the least.