How do I tell which processes are writing heavily to disk in CentOS 5?
I also like iotop
collectl may be what you are after. I/O statistics by process, among other things.
collectl --top io to print a top-like listing sorted by IO usage, collectl -sZ for collectl native output for the processes subsystem. Adding the --procopts t switch will show threads too.
As Richard Salts mentioned, IOTop will give you a UI with more detailed I/O stats, if you have a window manager and Python then use that. In either case though, if your kernel doesn't support it (2.6.20 or later is a safe bet) then neither program will work.