iSupr8 Levi's Film Workshop: Levi's iSupr8 Film app probably does the best at capture the finicky flickery flippity of those Super 8 cams of yore. It was just updated to include some Levi's-specific features like a denim-esque camera case and other more useful options like adjustable frame rates, customizable film stock (tweak scratches and vignettes), and more. It's probably one of the most powerful "Instagram-type" video recorders available for the iPhone.
Facebook Messenger: Think of it as a cross platform messaging service that enables you to easily talk to people on any platform-Android, iPhone, Facebook, SMS and everything in between. It's not dissimilar to Kik or WhatsApp in this aspect. Like Sam said, If your friends are on Facebook, they'll get your message in the Messages (or on their Android or iPhone). If they're not on Facebook, it'll be re-directed as a SMS message (they'll get a message from a random number saying CASEY CHAN SAYS ___ ).
Photo Stats: Statistics-pedants will love the Photo Stats iPhone app, which displays all manner of juicy info about your photo-taking, from what day of the week you're at your most prolific, to the time of the day and even what countries you took them in. $1.
Crowdmug: The premise is simple: offer cash for photos or videos of whatever place and people will answer. Let's say you're trying to decide which bar you want to go to and you're in the mood for some live music. You can post requests for multiple videos from multiple bars offering a couple bucks for each video. If all goes well, you'll have the information needed to make an informed decision and some lucky bar crawlers will be having a drink on your tab. It's a win-win. Free
Street Tag: It's an augmented reality app that turns your iPhone into a can of spray paint. You can set the color, width, and wetness of your paint and because it uses AR, you can tag graffiti on anything. Literally, anything. I just lit up the office floor, roof deck and my boss's desk and no one is the wiser. Stealth, baby! Free
New Yorker Goings On: In a nutshell, the Goings On app is the New Yorker's entertainment listings in app form. That means you'll be up to date with the theatre, art, music, dance, movies, restaurants, and night life scene. But there's more! You can read various New York-based artists wax poetic about the city and their own personal spots in the city and even listen to audio tours that guide you around the maze grid. Basically, if you live in New York and want to maintain some semblance of being "cultured", this should be on your phone.
OkCupid: The apps will locate other OkCupid users within your proximity, whether they match your interests or not (you can toggle the security settings, obviously). Once you've found someone whose profile catches your eye, you can either chat with them, swap some photos and arrange a date.
Bandito: Bandito gives you personalized news on the artists you listen to most on your iPhone. How? it scans the iPod app and then gives you the relevant news, blogs and links in the app. You can tweak it to how you want it and check out 'The Hotlist', which is a list of popular artists you might care to learn more about. Free.