If you'd like to keep them the best place would be in the ground. Snap off any seed pods where the flowers were, but keep the leaves on - the plant will need them to build up a strong bulb for next year. Water them if it's dry & you could feed them too a couple of times (water them with soluble plant food or mix some slow release bulb food into the earth where you plant them). The leaves will die back in their own time, but the longer they are on the bulbs the better. Don't tie them up or cut back.

If the leaves are already cut off, or badly twisted and bruised, they will still come up next year, but they may not bloom until 2012. Also be sure to plant them where they get at least 6 hours of direct sun a day, or they may never bloom.

That's interesting Tugbrethil, here they're often grown under trees. But perhaps they get enough sun as the trees are deciduous.

I dont think 6 hours is necessary - mine flower well (a little later) in quite considerable shade. Perhaps depends on the variety.

Hmm. I wonder why they don't seem to like shade here? If we're talking trees, only 1 out of 10 trees here are deciduous, so maybe that's the problem. Daffs definitely don't work on the north side of the house, here.