There are a whole bunch of such things at the Microsoft TechNet Windows Sysinternals Utilities page: http://technet.microsoft.com/en-us/sysinternals/bb545027.aspx
I downloaded Process Monitor, and played around with it a little, saw it had a log feature and thought why not, might come in handy one day, so I turned it on. Didn't occur to me that I might need to specify a maximum file size for it, though. I had a full system virus scan and backup scheduled to run during the night, and the next morning found a screen message warning that my hard drive was full. Panic ensued. Could only run chkdsk at reboot, and that took about 2 hours. It found nothing wrong. Finally resorted to a desperate act: using Norton AV Disc Clean utility, which suggested that a good way to free up disc space might be to delete the 185 gb procmon.log file. Which, of course, worked like a charm!