If you use Evernote, or even if you don't, you may want to consider using Skitch, which is an image annotator. For example, you can take a photo of notes written on a whiteboard or easel, annotate it, and then save it to Evernote and/or share it with other applications. You can draw on or add clip art to the top of a photo to point something out and/or add some fun to your photos. You can also add text, mark up text, and zoom and crop images. When you're finished, you can post images to social networking websites from directly within the app.