People might be interested in this:
Little Snitch
It detects any outgoing activity, and you configure it to allow only what you want.
From the reviews, I have yet to see anyone claim there was any spyware detected on their Mac. But people seem to be upset that their purchased programs are 'phoning home'. I would think most of these are just checking for updates.
At any rate, if some form of spyware
were to get into your Mac (still no existence of any in the real world AFAIK), this should catch it if it tried to send out passwords or anything.
-ERD50