slapped a 10 or 15lb grey plastic weight from an old crappy weight bench set I used to have. Then I put the base back on.
It takes about 1 minute for each stand and makes the stands about 5x as stable. Granted, it's not perfect, but for crappy weights that everyone seams to have in their basement, you really can't beat it.
And a LOT cheaper than the alternative, sand bags. Have any of you priced sand or shot filled bags at your local tech supply shop? Few of the pro audio places carry them, but all of the film and lighting supply shops out here have them in all shapes and sizes and they are absurdly expensive; like $40 for a 15lb bag!!! $30 for 10lb, $20 for $5lbs. I am NOT exaggerating!
Unfortunately, sand bags are more flexible than old barbell weights and I really need to have a few on hand at location gigs. But for studio guys who are just trying to stabilize a mic stand, go for the plates; you'll go broke buying sand bags....