What .dwg Viewer Do You Use?

I'm looking for a Freeware/Shareware Autocad .dwg viewer which will allow you to measure dimensions/line lengths etc.

Anyone know of anything free/cheap with this ability?

I have Autocad, but not all of my co-workers do. Many of them would benefit from occasionally being able to open a cad file and take some quick takeoffs. They don't do it often enough to justify the cost of the Autocad licenses. There are plenty of free viewers out there, but I'm specifically looking for one that can take measurements to determine square footages, etc.

I'm looking for solutions for in both Windows and OS X...

What you're looking for is an on screen take-off tool.

Am not aware of any freeware that allows this capability unless you're a member of whatever online planroom may be in your area.
Here in Dallas it's ISqFt and use to be CIN.

There are a few good pieces of software for this, but anything beyond a trial period is going to run you $750 or more per machine.
On Center is one, we use Vertigraph and digitizers.

For viewing drawings in OS X, I really like Solidworks free eDrawings Viewer. I have autocad and actually prefer to use eDrawings if I just need to take a quick look at something. It opens them lightning quick and is as basic to use as Acrobat viewer.

The only thing it's missing is the ability to select two points and calculate the distance between them.