I have several apps and app pools in IIS6 / Win 2003 Server.
Right now, one app pool is running at around 500 MB of RAM usage in TaskMgr. I'd like to know which app pool that process represents.
How can I find out?
Check out this article, Listing Running Web Applications Using Iisapp.vbs (IIS 6.0) ,from Microsoft's TechNet site.
Hope this helps some.
Try looking in Component Services under Running Processes. This should show which processes and their associated process ID's are running for which web sites and in turn you can look in COM+ applications to find the app pool for that web site (you could also look at the properties of the web site to determine that app pool after you've identified the process.
EDIT
There's probably an easier, more elegant way of doing this, but as I'm not really an IIS person this is the way I do it.
Check for the PID of the w3wp which is consuming the memory.
C:\windows\system32
iisapp.vbs
This will give you the app pool name and corresponding PID. Compare both the PID's and you will know which app pool is consuming the memory.