I haven't read all the other replies, but here's what I do (I run a home day care with my own toddler and three full-time kids).
After lunch time, the kids nap for usually one and a half to two hours. My daughter is phasing out of her nap (which works for me because I am trying to wean her from breastfeeding -- she'll be 3 in August), so I set her up on the couch with her favourite movie and a portable DVD player (I don't feel bad because she doesn't get much tv other than that, and my day care is very educational with a weekly theme and preschool learning activities).
I will take half an hour and do my workout. I do Pilates from Cassey Ho at www.blogilates.com. I am following her beginner workout calendar and it's about half an hour a day.
My day care closes at 5, and on Mondays my husband comes home from work at 3, so at 5 I do a half hour of cleaning and then make supper. On Tuesdays, Wednesdays, Thursdays and Fridays my husband gets off work at 6. So I have an hour to clean and cook. If I can fit a half hour of cardio (I love Zumba, and have a Zumba XBOX Kinnect game that I love) I will do it then, or we will go for a big family walk with the dogs after supper.
I also try to do stretching with the kids once a day after nap time. We do some fun and simple stretches to wake our bodies up and make us feel good.