[jotapes]

Mark,

I'm assuming that you're on Lion... You don't have to create a folder for Omnigraffle. In your finder, hold the OPTION key and go to the "Go" menu. The Library folder should appear among the choices.

If you go into that folder, you'll see that there's already a Omnigraffle folder, and within that, a Stencils folder. Once you put your stencils there, they should show up. At least it worked for me.

If you're not on Lion, then ignore this ;)