Assign value to edge?

I was wondering if there is a function or script that allows you to select an edge, and assign it a value (in this case blender units) Something like in Solidworks if you know what I am talking about. I am aware of the values when transforming. Right now my work around is extrude, enter my value and axis, and continue. What I am looking for is to select a previously made edge, and assign its length (numerically).

Simply, tell blender to make an edge a certain length?