iToony lets you decorate your photos with speech bubbles, captions and drawings, providing a fun tool for anyone who has time to spare and wants to amuse their friends. The $2.99 app from developer Standard Widget Corporation lets you decorate photos from your photo library or from photo sharing sites Flickr and Picasa. The iToony website provides a detailed and comprehensive guide to all the features.
I found the app easy to use except for the Undo option, which does not seem to work too well with the iPhone's touch interface. There are improvements to be made but overall it works well and let's anyone who is into sharing pictures with funny quotes and captions go wild.