Recently I taught myself (with expert assistance from "Þríhyrnur og langsjöl", a.k.a. "Three-cornered and long shawls") to wind a hank of yarn into a center-pull skein by hand:
(See these wonderful heathery flakes of blue and pink? This is one yummy yarn, which I got fresh at the Ithaca Farmer's/Farmers' Market (I never know) last fall).
Even the bottom came out pretty flat:
I´m pretty excited about this technique, since I a) hate having balls jumping all around the room when I'm knitting and b) don't have a "real" ballwinder (hint hint). Hopefully I can get the time it takes me to wind up one of these down to, say, less than one full evening, and then I might even use this technique exclusively!