[bad mechanic]

At the bike shop I worked at we had a tool made by Park which I believe they designed for truing chainrings. I whipped up a drawing of it below. Does Park still make this? Does anyone know Park's number for this tool?

 

[sanjuro]

It is a brake toe-in tool: http://parktool.com/tools/BT_3.shtml

 

[recidivist]

There are also those disc straightening tools (what're they called ... chopstix?), which would be somewhat similar, though I have you to see on from Park.