You already got a script that will help you to solve your issue, but if you can check this: http://miauumaxscript.blogspot.bg/p/miauus-script-pack.html Search for miauu's Scale Tool and watch the videos.
I've sort of got a tool that does this. You would run the script. Select the first object and get the size on the axis you want. Then select the box you want to scale and press Set Size. I think blender can snap scale to vertices the way you are intuitively thinking of it.
@monster ..dude, that worked. Thanks for the script. I'm curious though, since you mentioned Blender, were you a 3ds max user who is now a Blender user? I've been thinking of making the switch myself, but little things like the interface and not having FFD have been holding me back. Anyway, thanks for the help.