Add to Any actually encompasses just about all the ways to socially share something, but Twitter is included. They take care of most everything for you, including the ability to change the colors of the plug-in to match your blog itself
Help readers share, save, bookmark, and email your posts and pages using any service, such as Facebook, Twitter, Digg, Delicious, and over 100 more social bookmarking and sharing sites. The button comes with AddToAny’s customizable Smart Menu, which places the services visitors use at the top of the menu, based on each visitor’s browsing history.
Localized languages and Google Analytics integration are also part of it. Bookmarking, email and just plain old network sharing are a key part. While not as Web 2.0 slick as some newer ones, this is very comprehensive. Considering it is download a couple thousand times per day, you might want to take a look and see if the features are what you need for your WordPress based blog.