I do work on Linux and most of my coding in vim, so er, a lot?
Edit: I guess I should play along and add some tasks. They're not much different from the others' though.
Source control! It's handy and easy with a few keystrokes. Just haven't met a visual interface that was as convenient (with some exceptions).
Builds. Anything that involves a lot of scripts, really. It could be bound to a button in a visual IDE, but then what about the times I need to run it once with a slightly tweaked configuration? Now I have to open the command editor to change the command and remember to change it back after I run it.
Various tools that don't have a graphical interface to begin with.
I spend most of my time with my hands on the keyboard. Most of the work doesn't involve a mouse and many of the tools don't for most of the time either (keyboard shortcuts, huzzah!). I find that it's a small mental break for most of my work flow any time I have to move a hand to the mouse. Now, if more of my work already involved the mouse my tune would probably be different--any time I'm working in Blender or GIMP I have one hand permanently attached to the mouse, but there it makes sense. Programming? Almost everything is keyboard shortcuts and typing. Mouse is... foreign. The terminal is just a natural extension at that point.