OnlySkillups adds another filter possibility to the Tradeskill window.
This addon has become obsolete as it is now available in the default UI
The filter can be toggled with the new button left to the "Have materials" checkbox. When enabled this filter will only show recipes that have a chance to give a skillup. This makes it easier to find those recipies that will improve your tradeskill level, but are lower in the list.
Have fun