I'm quickly becoming addicted to a new photography application on my iPhone called Instagram. All you do is snap a picture, apply one of the many creative filters, and then easily share it to all of your favorite social sites. You can also geotag photos and check in to foursquare all in one shot. It's also got the underpinning of its own social network, letting you view, favorite, and comment on the most popular public photos. It combines the fun of Hipstamatic and the simplicity of Posterous, and it's free. I can't wait to see where the creators of Instagram take it next.
Instagram joins Hipstamatic, Pro HDR, and 360 Panorama in my folder of photo taking tools. You can see my reviews over at my Blippy page.