I've seen photos of females I have met - through swingers parties, etc - but none that I would say I know personally. However if I see any online that closely resemble someone I know I will save them and keep them in a folder in the name of that person.
So if I ever want to fantasise about a lady I worked with - let's call her
Linda shall we - I am able to whip out some nice porno pics and there she is.
Ex-girlfriends are even more memorable if you can find a lookalike porn star.