Good annotation/note-taking apps for an x201 tablet hackintosh?

[hackintosher]

I've got a working x201 hackintosh with a working tablet (after much DSDT-diving and installing TabletMagic). I'm so psyched to have a tablet hackintosh, you have no idea! But I'm a student and will be annotating PDFs and note-taking math-stuff, like graphs and so on. Does anyone have a favorite OS X app for tablets? I've tried a few and they're...underwhelming. I'm thinking of something like Xournal for Linux, which is lightweight, and free (did I mention I was a student?).