I've spent around a year building a Facebook, Twitter, MySpace & LinkedIn iPhone app, which aside from the API hell, has been a pretty fun experience! I think it's turned out really nice. It's been a technical challenge to sync not only a single address book, but also your address books on all the social networks, but in hindsight, I'd do it all again. I'd love to know what HN think's of it, the app URL is:http://itunes.apple.com/app/friends-plus-facebook-twitter/id407846513?mt=8&ls=1
Here are some promo codes, not sure how long they will last:
WPTA4M99L3YF
MR39LWPTKNYT
ME346Y3TPNY9
TY69MJN6ARYY
EKR3MAHFJAP4