Many of the things that we have to remind ourselves to do, or bring with us, throughout the day are tied up in a place as well as a time. Dropp [Free, App Store] is a unique app that functions as a location-based reminder app that will trigger when you enter an area. But it also has a cool secondary use as a personalized messaging service that allows you to drop text or picture messages in an area that will be picked up by friends or family automatically.

To set up a ‘dropp’, you launch the app, tap the drop button and add a text or picture message. You can set a dropp at any location, including your current one. There are several use cases right off the bat that make it a cool tool to have to remind yourself to do things. Being able to set a message at work will allow you to remind yourself to do something as soon as you get there. A picture message could be used to remind you to get milk at the store and indicate the exact type and brand with a shot from your fridge.

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If you know that you’re the kind of person who is going to forget to ask a date how her mom is doing you could set up a dropp for yourself at the place where you’re going to meet. When you get there, a note will pop up that you have a dropp, tapping the notification will launch the app and unlock the message because you’re in the area.

The best things about Dropp for me though, are the possibilities for communication once you start using it with friends and family and not just yourself. If you want to send your wife a nice little note that unlocks when she gets to the office, just set up a dropp for her work address. Add a picture or text message wishing her hugs and kisses (or whatever, something more manly perhaps) and send it off. When she gets there Dropp will send her a notification that she has unlocked it and she’ll get a nice surprise to start her work day off right.

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In addition to private dropps, you can also leave public messages for anyone on your friends list, which you can populate several ways including Twitter, to find. Dropp’s creator Richard Felix says that they plan on expanding this, allowing you to find and unlock sponsored caches that may deliver a promotional message or discount to you if you choose to open it.

If you’re interested in seeing what dropps have been left in your area you can simply fire up Dropp and get a list. You can then tap on them to see where you need to be to unlock them.

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On top of this cool mechanic is a very nicely designed UI that uses completely custom elements. Its simple and smart and offers just the right amount of graphical flair without getting too complicated for its own good. Even the standard map view is tweaked just slightly with a grid pattern to make it more unique. The tabs give easy access to the map, friends, activity and new dropp buttons. The icon is also very well designed, its got a very, well, iconic look. High marks across the board for the look and feel of Dropp.

The concept of Dropp is a simple but clever one, private or public messages with text or pictures attached that are unlocked by visiting a location. It’s such a clever idea that some basic version of this functionality is included in Apple’s Reminders app in iOS 5. The execution of the feature is much nicer in Dropp than the Reminders app however and the ability to attach an image to a dropp is super fun.

If you’re intrigued by the idea of being able to send yourself, or your loved ones, messages that are unlocked by location then you owe it to yourself to check out Dropp. It’s easily the best implementation I’ve seen of the concept so far and the UI is gorgeous. You can snag it now on the App Store.