If you are thinking about writing the next best tool to access twitter or use the data in some creative way then the best way to start is with some sample code and API references.

There is tons of code out there and lots of it is open source so you may add it to your code.

If not then you can get information about the API that Twitter exposes and pass your data by the methods they require.

Some applications will require a registration so that a large volume of users can run your ap at the same time. If you are writing it for your specific site and don’t intend to release the code then you should have no problem.

Here are some decent resources.

Use PHP to convert Twitter to RSS
http://www.ibm.com/developerworks/opensource/library/os-php-twitter-rss/index.html

Twitter API Documentation
http://apiwiki.twitter.com/Twitter-API-Documentation

C++

• QTwitLib by Bradley Lackey & Maks Zolin. C++ library for Linux, Windows, and Mac.  Currently in beta.

C#/.NET

• Yedda Twitter Library by Yedda. Every Twitter API method has an equivalent .NET method in this wrapper library.
• TwitterooCore API by Eric Willis/RareEdge Design Group. Binary .NET library that can be used in any .NET project.
• Twitterizer originally by DigitallyBorn, but now open source. Written for .NET 2.0.
• tweet# by Daniel Crenna. “100% coverage of the REST and Search APIs”.

Java

• Twitter4J by Yusuke Yamamoto.  An open-sourced, mavenized and Google App Engine safe Java library for the Twitter API, released under the BSD license.
• java-twitter by DeWitt Clinton.  Pure java interface for the Twitter API.
• jtwitter by Daniel Winterstein. Open-source pure Java Interface to Twitter.

Perl

• App::Tweet by Joshua McAdams.  Tweet on Twitter from the command line.
• Net::Twitter by Chris Thompson.  Perl interface to Twitter.
• Twitter::Shell by Daisuke Maki.  Twitter from your shell.

PHP

• My Twitter by Andres Scheffer. Set and retrieve a Twitter user’s status.
• Twitter by Felix Oghina.  Update the status of a Twitter user.
• TwitterLibPHP by Justin Poliey.  Manipulate a Twitter user account.
• Arc90_Service_Twitter by Matt Williams.  Open source Twitter API client.
• PHP Twitter by Aaron Brazell, original code from David Billingham.
• PEAR Services_Twitter by Joe Stump and David Jean Louis.
• PHP Twitter by Tijs Verkoyen. BSD Licensed.
• Twitter-async by Jaisen Mathai. Wrapper for Twitter’s OAuth API which provides asynchronous calls.
• API CodeIgniter Library by Eliot Haughin.

Python

• python-twitter by DeWitt Clinton. This library provides a pure Python interface for the Twitter API.

• python-twyt by Andrew Price. BSD licensed Twitter API interface library and command line client.
• twitty-twister by Dustin Sallings.  A Twisted interface to Twitter.