It wasn't ridiculously big (28x16x6"/71x41x15cm) but it turned out to be heavier than it looked. I wasn't going to leave it there because I'd forget about it by the time Vogon got home, so I lifted with my legs and carried it back home while Laurel skipped around ahead of me with my padded envelope of office supply goodness.
When I got upstairs, I pulled on the label to see the packing list. Guess what it was? A bench grinder stand.
Next time I will look at the label first. Sheesh.