Oink is the first app from Kevin Rose’s startup, Milk. You might recognize Rose from his previous success story, Digg. The young entrepreneur made a fortune off of his sharing service. Now he’s hoping he has another hit on his hands.

Oink certainly has all of the makings of a hit title: the ability to follow and share photos of things with other users, image filters, and Twitter/Facebook integration. But the photo-sharing software space is already pretty crowded…

So what exactly is Oink? And how does it differ from the competition?

“Oink is an easy way to rate and rank the things around you. Instead of just rating places, you rate the items inside. You could easily find the most popular items on a menu and see if a friend has tried anything there. Then if there’s something you like, it’s just a single press to rate it and share it with friends.”

Although the app is available to everyone, the ability to create an Oink profile is by invite-only. You can still search and browse through photos without a profile, you just can’t share or rank them. It’s a temporary restriction while Rose and team iron out all the bugs.

The good news is that you can request an invitation, and the turnaround time is less than 24 hours. I received my Oink invite on Saturday, and have been using the app ever since. It actually helped me discover a really good nearby burger joint that I didn’t know existed.

Keep in mind though that I live near Portland, Oregon. You may not find anything close to you if you’re in a smaller town. But as more and more people join the service and start ‘Oinking’ things, you’ll obviously have a better chance of finding things nearby.

If you want to check it out, Oink is available for free in the App Store. As aforementioned, it’s easy to request an invitation from inside the app (just enter your email address). Will this be the next hit iOS app? You tell us. What do you think of Oink?