Apart from selling your twitter account, you could use twitter effectively to communicate with your followers. I belief Twitter is the most successful micro-blogging platform out there with tones of third (3rd) party twitter application after the release of their API. Each day I am finding more and more Twitter Application and you could browse a list of Twitter Application Here.
This is where I started twittering and a very crucial application if you have a blog or a website that releases information via rss feed.
Kevin Doyle recommended twhirl – It is a better desktop application to keep updated with your twitter. It has various functions than enable you to use twitter effectively. Wonder why Twitteroo is the official software for Windows Twittering.
This is a desktop application to be in touch with your twitter and the people you follow. There is few alternative windows software that I have yet to try. But this is on twitter official download for Windows platform.
Search your location to find more friends around you. You do not necessary need to search for your own location. If you would like to look for friends overseas, you could do that too.
I have actually used twubble to add more friends and the process is very fast. Twubble simple find friends of your current friends. When you follow some people, eventually a portion of the people will follow you as well.
This is a very cool service showing who is updating their twitter account with their geographical location on the world map.
Search a person twitter account for a certain keyword
TwitSig allow you to add your twitter update on forums as signature. This is because it converts your twitter post into image.
Send message privately to a specific group of twitter friends. But firstly, you will need to create a Twitter account to use it as a group.
TwitterMeThis is an interesting idea. It is actually a contect whereby the first who reply them with the correct answer will win $5 to their paypal.