In the spirit of memory mapping, though, you can use colors and scrawl and draw arrows, things that are hard to do while typing. The Maemo Pad+ or whatever it is called also has the scrawling feature. I'm still looking for a nifty note taking app like 1) thebrain or 2) brainstorm or 3) kdissert or 4) vym or 5) mindjet. And there have been many others like them. Xournal has potential.