An epic Reddit thread entitled "These fucking scissors" has lab-techs and scientists compiling an exhaustive, definitive list of all the weird, useless crap that has accumulated in their labs, and the reasons why none of it can be thrown away. A couple of my faves:
Specialized Glassware of Uncertain Use
You don't know where it came from. You have no idea what it does and you can't find it in a lab catalogue anywhere. Even your advisor doesn't know who bought it or what it's for. It eats up space that could be put to better use for graduated cylinders or Erlenmeyer flasks, but in a way, it commands a sense of respect, even reverence. It has always been there and always will. You are sure it was unspeakably expensive when it was purchased, whenever the hell that was, and for that reason no one in the last 30 years has had the heart to throw it out. Your advisor thinks maybe someday someone will use it again. You think maybe someday you'll steal it and make a sweet bong or something out of it. But you ultimately find you can't. It's a piece of history, it is beautiful, and even though you don't know what the fuck it is for, you want future generations of laboratory serfs to have the opportunity to ponder its purpose.
Expensive, Useless Stuff From Back When The Group Had Money
Years ago somebody needed 10mL of a super-expensive reagent. Having just gotten some grant money, they bought 2L of it. Now you have $2000 worth of something you will never use, but you can't throw it away because it's too expensive.
Vintage Liquid Chromatograph
It used to belong to the Plant Biotech department, but they got funding for a new one, and your professor is sure he'll fix it up as good as new and get great GPC results out of it. The white elephant has successfully migrated into another two years of idleness.