Savvy Metro riders know that their TAP cards are the key to great discounts around L.A. courtesy of Metro’s Destination Discounts program. We do our best to keep up with the latest deals in our weekly roundup of discounts, but it can be easy to forget what’s available when you’re actually out and about.

Enter Vidappe (pronounced “Vid-app”), a clever app for the iPhone (coming soon to Android) that uses the iPhone’s GPS to locate nearby deals and remind users to take advantage of the savings.

Vidappe was created by Star Li, a 2010 Cornell University graduate who hatched the idea while in school. Star and Vidappe are not affiliated with Metro.

The app isn’t specifically designed for Metro deals — in fact it has a database of programs from around the state and country. But users are in control of what deals they want to see. Here’s how it works: after downloading the app, you register for the service (the company tells me all info is kept private), subscribe to the L.A. Metro program and then adjust the sensitivity (i.e. if you live in an area dense with deals you can set the program to alert you only when you’re within a block or two of a deal).

After setting things up the app will send out a gentle alert when you’re in a proximity of a Destination Discount. You can also turn off alerts and just use the app to view of map of nearby deals. I’ve been using the app for a few days now and have found it to be a great and unobtrusive way to remember where I can use my TAP card for discounts.

Interested? The (free!) iPhone app is available for download here and the Android app should show up in the Android Marketplace in two weeks.

If you try it out, let us know what you think!