I launched http://www.notaplex.com for the iPad: "Nota plex - write notes, lists, and outlines." None of the note-writing apps that were available were what I wanted, so I learned iOS programming and wrote this one. Also I got to use old-school lex & yacc programming for the in-line calculator part.
I've always wanted to use something like that to take notes quickly, does it combine well with a bluetooth keyboard?