How many of you hold on to equipment you don't use, simply because you're 'attached' to it?

I'm cleaning out my display case of everything that doesn't get used, and I've come to my Nikon FM. Its clean, it works, and its a nice little kit. It hasn't been shot since November of last year, and now that I have an F100, the likelihood of me picking up the FM for an outing is slim to none. The conveniences of the F100 are just too nice. So it just sits there, in the display case.

Some days I want to sell it, some days I don't. I know that it should be somewhere where someone can enjoy it and USE it, but I have become attached to it and knowing that if I sell it I may never find another one like it keeps it where it is.

How do you guys ration with keeping/selling things?