I found a really great application, which works for both Mac and PC. It's called Poladroid. It easily turns your JPEG images into digital polaroids. But it's quirky. Like an actual polaroid, these polaroids take time to develop, and if you shake it, it develops faster. But the wait is worth it, because the images it produces are great.
It's still in beta testing, though, so it has a few problems. The application doesn't automatically come to the front when switching to it from another application. But other than that, this is a brilliant application.
This app is designed for people who have an interest in old, lo-fi photography, for people who are nostalgic about a dying medium, or for people who just like interesting looking photos. This is a seriously fun app for anyone who likes to play with images.
Poladroid is already making its way around social-networking sites like Facebook and Myspace, but it's still in its Early Adapter stage. It's starting to tip. It's not super popular just yet, but I imagine it soon will be, considering the growing photo-editing trend (Picassa, Picnik, etc.). I anticipate that in a few years, there will be editors like this for tons of other types of old photos. Already there is one to make photos look like they were from the 1800's.
