In ArcGIS 9.3 there was a tool called Extend/Trim Features that allowed you to select multiple segments and extend or trim them to a feature.
In 10.1 that seems to have been moved to the Production Mapping Extension at a hefty price. It was replaced by two tools that don't seem to have the same functionality as the previous versions tool.
My question: Is anybody aware of an add in or way that I could create this functionality with python or a custom tool?
The old tool can be found referenced HERE, there is also a screenshot of the tool location from 9.3:
Essentially, it did both of the functions that are shown in @Jakub's answer.
It looks like the same tool from 9.3 was moved to the Production Mapping toolbar in 10.1.
There seems to be an ESRI Idea out there suggesting they bring it back, and that I'm not, in fact, imagining that it used to be this way.