Sprue hoarder here as well!
It’s precious as I buy very few new plastic kits these days.
Mine see repeated use as warmachine paint holders glued to invisible points. As @Jasko pointed out in hobby hangout 1.
Also making rock shards/crystals out of them is a common use. First decade old attempt for a necrolith colossus.
More recent Tjubbly Fablanquin crystal rock turtle.
I also use them as buildings in BFG orbital cities.
Endless terrain options too. Junkyard basing, etc. Here’s an old but perhaps not the worst idea.
