The app works pretty much like the iPhone camera app, except when you take a picture (or select an existing one) it will automatically add a reminder for the next day. You can, of course, change the reminder to any time you want (in five minute increments) and you'll receive alert when that time happens. The downside is that the alert won't contain a photo (in the way an MMS alert does) but once you acknowledge the alert you'll be brought to the photo in the PhotoMind app. In addition to keeping these reminders on your iDevice, you're also able to share them via email.
PhotoMind will set you back $1.99, but that gets you a hybrid app for iPhone/iPod touch and iPad.