*Appetizer* is my [App.net](http://alpha.app.net) client of choice. It is still in its early stages, but it handles the basic App.net functionality[^mo] well.
[^mo]: I also have tried *Mention* and *moApp*. *Mention* is just not my style, while I feel *Appetizier* handles things a little better than *moApp*. Also, the *moApp* developer was kind of offensive on App.net recently and that makes it hard for me to support him.