Is there an utility which can profile and report on the activity of a single process? Activity monitor can report on a single processes's disk and cpu usage at a single point in time.

The "Sample Process" feature is good for debugging, but doesn't provide easily digestible information.

Apps like iStat are just pretty layers on top of activity monitor.

Is there an app for OSX which will sample a Processes's resource use over time and then provide a report with nice graphs?

Something like DaisyDisk but for cpu and disk usage for a single process over time?
I think BigTop is what you're looking for. It comes with the Developer Tools (which are on the install disc that came with your Mac)