Here is list of some useful resources to create twitter applications.
HTML
Javascript
PHP/AJAX
- Twitter: send message from a PHP page using Twitter API
- Authenticating Twitter API calls with PHP & jQuery
- Sending Authenticated Data to the Twitter API
- Update your Twitter status using your instant messenger
- Proxy for Ajax requests (Twitter API)
- Twitter JavaScript API – The Beginning
- How to create a Twitter widget/client with unobtrusive, degradable JavaScript and FakeJAX
- Google Talk Status to Twitter
- PHP + Twitter + Google Calendar + SMS
- Creating a simple Twitter Reader(Client) in 5 minutes!!

Ruby
- Rails Template: Create a Twitter Application in Seconds
- How to Twitter in Ruby on Rails
- How to Build a Twitter Agent
- 5 Tips for Using the Twitter API With Ruby
- How to Parse Twitter XML in Ruby on Rails
- Be Notified of New Twitter Updates by IM
Java/JSP
- Write your own Twitter application
- Playing with the Twitter API
- Accessing Twitter with Java using HttpClient
- Twitter Access in Java
OTHER
- Twitter JSON/JSONP API URL
- jQuery Twitter API plugin
- Building a Twitter widget, part 1: setting-up the code and displaying a single status
- Building a Twitter widget, part 5: publishing data to your account through authentication
- How To Create A Twitter jQuery Plugin




Thanks for the list.