There are a number of handwriting apps out there, with save to dropbox. Just take a look around the app store.
I've tested one OCR app, Writepad, which sucked so unbelievably badly it would have been funny had it not been a waste of five bucks. Note Taker HD was, for me, the best of the handwriting (non OCR) apps, but in the end I abandoned all of them and returned to the keyboard. I found myself being considerably faster typing than handwriting.
The screen of the iPad, and the iPhone even more so, is simply too small to accomodate handwritten notes.