Duelpic lets you challenge another Instagramer to a photo duel.
Voting is conducted by anyone using the app, simply move the app icon to the photo you prefer.

Duelpic by Duelpic Inc., free in the Apple App Store

Compatible with iPhone 3GS and later, iPod touch (3rd generation) and later, and iPad. Requires iOS 5.0 or later.

Duelpic for the iPhone could be your latest guilty pleasure.

As addictive as Draw Something was for that first week you played it, Duelpic is easy to understand, quick to play and lets you interact with your Instagram buddies – and your entire Instagram library of photographs – in a new way. We had a quick play with the new app and could hardly put it down.

The concept is simple: start a duel by choosing an image from your Instagram feed, then give your duel a category name. Type in another user’s Instagram handle into the opponent field (if they don’t have Duelpic yet, you won’t be able to find them), or check the box next to Random Opponent to challenge anyone with the app. 

Once a duel has begun, you’ll see it listed on the home screen. If you're challenged to a duel and don't have a good response in your arsenal of Instagram photos, you can also choose to take a new picture using the Instagram in-app camera.

Duels are voted on by all users. You can vote for photos within Duelpic by tapping the menu button in the upper left, then Vote. Voting is so fast, it’s a big part of the app’s appeal. Move the logo to your favorite image to cast your vote.

As others vote for the duels you’re competing in, your won, lost and tied tallies will be updated on your Profile page within the app.