Granted, I am a sucker for the wood/brass combination, but this little gadget is just plain clever.
Stanley once made a tool called the No. 1 Odd Jobs tool -- that's what this tool is based on. It's a marvel of measuring and marking.
It can be used as a T-square and mitre square as seen at left.
Here it is shown being used to scribe an arc.
Here is is being used as a depth gauge to set the height of the blade on table saw.
Of course, you can use it as ruler too (it's maple with brass edges).
Check out all the details on the Odd Jobs Layout Tool. Oh...and order one for me!