Most of us have a thing about swatching. It takes time, and I want to cast on NOW!
But here’s the thing: I’m a product knitter and I like things to fit. Which means that I swatch for almost everything (the exceptions being scarves and shawls and other things that wrap instead of fit). Which eventually means that I have lots of swatches laying around.
Sometimes I throw them away (after the project is finished. I don’t dare tempt the knitting goddess that way!). Sometimes I repurpose them into a coaster or a mug cozy.
If you really love Tetris, I suppose you could start a swatch afghan (Swatch-ghan?).
My personal downfall is laundering the swatch after I finish it. Instant gratification is so close, but I know that unwashed swatches lie way more than washed ones do, so I wash it and wait for it to dry, and finally FINALLY I can start my project.
But only if I got gauge.