Born as an Ubiquity first contact for me, these commands are now outdated. Twitter interaction is no longer required. And buxfer's commands are to grow into more actions (e.g., spend, receive, loan, borrow and postpone-spend and postpone-receive). So for the updated commands head-over to the Ubiquity commands page and choose the new commands.
The remainder of the page stays here for historical reasons :)
These are two Ubiquity commands, for Firefox.
They allow to easily add a transaction in Buxfer, using its remote API. The name Twixfer comes from an alternative way to add it, by sending a message to Twitter (assuming you have an account), using only the Twitter API. The last method is there as historical reasons, and will remain there as an example, solely.