i have the PERFECT workout for you on my blog! no machines needed!!

http://movesnmunchies.wordpress.com/2011/02/02/cheers-to-a-new-start/

you can check  out others here too:

http://movesnmunchies.wordpress.com/the-moves/

Good question! You can do stair climbs, timing yourself and doing various sets of running and walking up and down them. You can do squats against a chair or wall too. You can turn cans or jugs of water/milk into weights.

Here's a Good Housekeeping article about some great at-home workout ideas!