iTester app for iPhone and iPad
iTester is a note taking tool meant to help during exploratory testing sessions.
It saves your notes in a .csv file that follows the same format as Rapid Reporter (http://testing.gershon.info/reporter/) and you can either email them to yourself or upload them once you sign in.
You can use the microphone (shown when the keyboard is displayed) to record your notes during each session - this will save you time and make your note taking experience better.