http://blog.tweetalicious.com/2011/06/how-to-start-your-first-twitter-application
Do you have an idea for an application that works with Twitter?
It really sounds great and you have a passion to build it. However, you should investigate its feasibility and limitations first with researching and understanding the Twitter API.
Twitter provides its data access through the Twitter API, and developers can build applications that extend or customize Twitter features with it. Lots of third-party Twitter clients were introduced utilizing the Twitter API, and therefore, their features are limited by the limitations of the API.
For the most part, the Twitter API consists of 3 big branches - REST API, Streaming API and Search API. Developers, who are already exposed to Web Services, such as REST or SOAP, won't find any trouble in using the Twitter RESTful Web Services. The big issue with utilizing the REST API comes from the API Rate Limiting enforced by Twitter. Twitter imposes Twitter API clients to make a limited number of calls within a certain time period. For example, Search API calls are recognized as anonymous and the Rate Limiting works based on the IP of the host. Authenticated API calls are measured against the authenticating user's rate limit and OAuth calls are permitted 350 requests per hour. Streaming API comes from the demand for getting over the REST API Rate Limiting, and it provides more liberal access on persistent connections. You may find the Search API to be a great utility if your application needs to search though Twitter data. Even Tweetalicious utilizes the Search API heavily, and it enables Tweetalicious to deliver personalized deals based on users' preferences.
A good resource for the Twitter API can be found at http://developer.twitter.com. If you decide that the Twitter API is the right direction for you, you can start implementing by registering the application at https://dev.twitter.com/apps.