The line of USB video adapters made by DisplayLink has a somewhat sordid history under Linux. In past Ubuntu releases, the process of getting them to work has been somewhat difficult, inspiring a number of past questions on this site:
However, there are some indications that version 3.5 of the Linux kernel (which is used by 12.10) contains better support for these adapters, which should make them easier to use. I currently have a single-GPU machine (it is an Nvidia adapter) with dual monitor outputs. I would like to add the DisplayLink adapter to drive a third external monitor. How can I set this up on Ubuntu 12.10?