This Instructable outlines how to grow fresh onion plants from discarded onion bottoms that would otherwise be thrown in the trash. You can theoretically create an endless supply of onions without ever having to buy bulbs or seeds, and if you're as big of an onion lover in the kitchen as I am, you'll have a full bed of onions in no time.
3 Week Update:
New roots have formed on the example onion used in this Instructable, and the starts of leaves are forming which can be seen by the two distinct rises at the top of the onion. This onion will more than likely form two plants just like fully formed example on this Intro page.
4 Week Update:
New leaves are forming above the soil, and it's clear that this plant will be able to be divided. It has now gone through a hard freeze in its pot sitting on a growing table.