I've seen some communities online where people collect and showcase passport stamps. Some even go as far ask requesting it from border authorities when stamp is not provided by default. But the worst (in my opinion) is getting those stamps from tourist offices (San Marino, Monaco) where border control does not exist or even street vendors (Machu Picchu). Getting random stamps in official document can invalidate passport.
I like stamps, but I collect them organically. If border authority has the protocol and need to stamp my passport - sure, otherwise - no thanks.
What do you do when travelling?