Perhaps I've been living under a rock, but today I was shown a neat script for IIS 6 that displays the process IDs and related application pools for all IIS worker processes. The script is "iisapp.vbs". It's just the trick when trying to discover which rogue web application is actually chewing up my resources (in conjunction with Performance Monitor and/or Task Manager). More info can be found on TechNet.
For the infrastructure people out there, this is probably nothing new. For devs like me, we probably don't spend enough time on TechNet to pick up nuggets such as this.
Theres also a nifty option to recycle a given app pool:
iisapp.vbs /a APP_POOL_NAME /r
The above example recycles by app pool name, but by process id is possible too.