Twitter Syntax on the Microformats wiki. Send these commands to 40404 and interact with Twitter on your mobile phone.
Designed for humans first and machines second, microformats are a set of simple, open data formats built upon existing and widely adopted standards. Instead of throwing away what works today, microformats intend to solve simpler problems first by adapting to current behaviors and usage patterns.
If you are interested in such things, there’s more information and examples at Microformats.org.