Ask HN: Review my iPhone App for Traveling with Friends

I've created an app called TripSplit that's meant to solve a simple problem: keeping track of who owes who money when you're traveling with your friends. As a frequent traveler, I've experienced this problem first hand many times. The design of this app is based off that experience, and I've used development versions on trips to great success. Now I'd like to see what other people think.

Any feedback is greatly appreciated.

http://itunes.apple.com/us/app/tripsplit/id349850196?mt=8

Here are some promo codes that will let you download it for free (I'll add more if needed):

  X66YTMF339JM
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  APAEA4RNPL9P
  FKF4NTL6XAKA
  LMJY67XK4XRT
  HPFFWXFNR777
  9XX3J7THTXMR
  94LJK3TM7JAH
  R3RRHFPMRNYL
  WM77KAWN4TJA

Below are a few ideas planned for future releases, but please feel free to suggest others. - Detect proper currency based on location - Record Location data for Events - Allow a picture or video to be attached to an Event - Allow pictures to be attached to Travelers - Address Book integration - Automatically perform currency conversions - Export Trip data via email