[Movable Write] is open sourced: http://blog.yjpark.org/blog/2012/04/22/movable-write-open-sourced/
[Movable Write] is not like writing on a paper, it's like typing with your finger/stylus.
Written words are fully editable, found out missed a word in last line, no problem, you can just insert new word anywhere. You can break long lines into paragraphs too, you can remove a whole word, or just remove individual strokes.
As it says, they are movable, you can zoom in or zoom out, the words will be readjusted automatically.
You write on a big panel, means it's both comfortable and looks nice. Just write on the panel, press one of the big space button after each word (it works best to use your thumb of the hand holding the iPad, works for left-handed too). use the scroll buttons for over-sized words. Other than the button, you can also double click on the page to toggle input panel.
There are multiple themes you can choose from, make your notes or letters looks nicer. Three free themes packed in, more will be coming soon.
Long press the page to enter preview mode, it's exactly what it look like if you send it out, PDF file will be created and sent as attachment, so it can be viewed everywhere.
Also it's fun to play with, check out the bubble font effect, your normal writings will be rendered as nice bubble fonts with just one switch.
And who said it's only for writing? With selectable color (actual color might be changed when switching themes) and line width options, feel free to paint with it, check the screenshots for some nice samples.
Tired of the plain typed emails? with movable write, it's so easy to have nice hand-written letters, your family/friends gonna love it.
Note: It works great with your finger, for the ones prefer stylus, you may check http://astore.amazon.com/pettyfuncom-20