This is a bit off the Unix road, but I believe most people interested in the answer are linux or unix users so here goes.
For a long time it seems that the number one process chewing up CPU time and memory is my web browser ( mainly firefox, but others too ). It is true that I have a lot of pages open at once, so I generally don't mind, but recently it's gotten to the point where the browser just bogs down the system, and when I close some pages some sanity is restored.
What would be nice is if there were some tool or plugin that would tell me exactly what web pages/sites are using the most resources.