I've only been a member of APUG for slightly more than a year and I don't know if this has been discussed, so...
Let's say you are a Nikon guy or a Minolta gal, you absolutely love the brand, BUT you have another slr from another manufacturer that you would never part with.
I've used a lot of slr brands but I would have to categorize myself as a Pentaxian, I just really like their slrs especially the Spotmatics up to the LX. However, I have a Nikkormat FTN that I really like and I can't see myself ever parting with. Not only is it a great camera but I can see it being very handy using it against muggers.