In Trouble in Terrorist Town servers that don't have it disabled to prevent prop griefing, I use the magneto stick to fling live grenades back at people/safely away/into far away openings. It's pretty sweet and a heck of a move when timed correctly! (I think my favorite use is chucking it just right so that smoke grenades explode right where a sniper's peek-hole is.) Another would certainly be using pistons to hide someone's house in Minecraft. They press the button to open their door an suddenly the entire house folds up!