CellWriter is a grid-entry natural handwriting input panel. It apparently includes an on screen keyboard too. It is usually built with libgnome2-0, but there is an --without-gnome option. I have not tried it on any device, but it looks like a good fit to the iLiad if it can be made to work. I came across it on jkOnTheRun, which references
Running Linux on the Samsung Q1U UMPC.