Never a software early adopter, I've recently been using Instagram. The interface isn't perfect (would love to be be able to edit/delete after posting, since I often post by accident; the Foursquare location search is unreliable), and I get a lot of failures on Verizon on my iPhone 4S, but it's been fun. Favorite filters are Polaroid Land Camera-esque Hefe, the high-contrast X-Pro II, and of course #nofilter. (Neat explanation of various Intagram filters at 1000memories.)
Follow me on Instagram--I take pictures of the same bullshit everyone else does.