Slightly off topic thread (prog to build tech tree)

[Steamsteam]

Question about tech tree

I was wondering if anyone knew a program that helps build visual representations of technology trees?

I am currently using the advanced papper and pen technique but its late and im lazy and looking for a better way of doing this... thanks in adv.

Edit:

Is there anyway to make a tech tree where it is required to have either building A or building B before you can upgrade? but not both buildings are required.