CollabraCam: CollabraCam links video from multiple iPhones and feeds them into another iPhone that controls live, multi-cam editing. Utilising a wireless LAN to get all the phones networked, the idea behind CollabraCam is that minimal-if any at all-post-production is necessary. $7.99
BoxyTunes: If you have a Dropbox account and use it to store music and podcasts, BoxyTunes makes it easy to grab those audio files on the go. BoxyTunes syncs up with your Dropbox account and lets you download music stored inside for playback on your iPhone or iPad. $2.49
RecognizeMe: RecognizeMe, a new jailbreak app, uses your iPhone 4's front-facing camera to scan your mug whenever you want to unlock your phone. Is it as discreet as tapping to enter? No-you probably couldn't subtly scan your face at dinner for some mid-meal texts. But it's surely a hell of a lot more secure, assuming you don't get sucked into some sort of Face/Off terrorism scenario. Jailbreak app.
PhotoForge2: PhotoForge2 might be a mere iPhone photo editor, but don't tell it that. For $3.99, you can adjust levels/white balance/colours, add effects filters, crop, resize, and embrace the power of LAYERS. Where you at, Photoshop? $3.99