Alexey Zakhlestins created php-twitterdata, a small library for working with Twitterdata in PHP. The idea is to embded machine-readable data in twitter that could be parsed and used in other applications. From Twitter Data website :

Twitter Data is a simple, open, semi-structured format for embedding machine-readable, yet human-friendly, data in Twitter messages. This data can then be transmitted, received, and interpreted in real time by powerful new kinds of applications built on the Twitter platform. Here is an example Twitter Data message:

I love the #twitterdata proposal! $vote +1

The part with the dollar sign, $vote +1, is a piece of data embedded using the Twitter Data format.

A sample usage of PHP-TwitterData :

Twitter applications could be more fun with TwitterData especially that you could easily parse and use data embdded in tweets directly in your application. Be sure to check Alexey's post, he provides details on working with the library and using TwitterData_Message, TwitterData_Frame and TwitterData_Tuple classes. The library is released under a MIT-style license.