Seesmic is a solid twitter application that you can use to do just about anything you can do on a computer from your phone. Very powerful with a lot of ways to configure and modify your twitter experience.

You can download it from the Market here.

Seesmic gives you a rich interface for accessing your witter account. From the main screen of the application you have the ability to check your timeline, your replies, your messages and even your profile. The menu strip also gives you further abilities  to drill into twitter.

Other tabs on the main screen give you a great look at what is going on within your twitter account.