I'm a big fan of using Post It notes in class for group work, brainstorming and other such collaborative tasks. After these types of activities I will often take a photo of a set of the sticky notes and source the pictures to the students. Often it can be a little tricky to read what it actually says on them though so when I stumbled across the official Post-it app this week I was pleasantly surprised.
Post-it Plus allows you to snap an image of multiple Post Its (apparently it can handle up to 50 at a time!) and digitises them for you. Pretty cool huh? The quality is generally good (naturally a thicker pen rather than pencil is the way to go) and if any aren't identified by the scanning process, you can manually identify them by tapping their place on the screen. This is handy if your lighting is poor or a student has damaged a note.
Once you've got your notes in he app you can actually edit them if needed and arrange them however you like on your virtual board. Sets can also be combined if you wish. Export options include PDF format and access to regulars like Dropbox as well as into Office software like Excel and PowerPoint.