It’s hard to argue with the awesomeness of the twitter phenomena. Their flexible API is a testament to how a great tool can used in so many ways.
The downside is that with such a widely adopted API there are about as many tools as there are tweet.
To cut through the noise, have a look at the following site for some of the best ones out there.
Personal tools of interest are desktop apps that manage various twitter accounts. Twhirl looks good, but the hunt continues…