Nike Training also has a great app for your phone and many of the workouts compliment the ones on here really well. You also get bonus workouts for using it...My abs are more defined than they have ever been.
I walked uphill to a park 1.5 miles away every day. My son loved the walk. By the time he was six months he would cry if we didn't leave at six. Also try getting a baby carrier. .. you can carry one and push the other. Just keep your back straight and belly in to increase core toning. There are also stroller exercises you can do. I will try to add a baby routine if you want to follow me.
I just started working out a month ago and am down a whole size and getting ready to go down another. I swear by Zumba. Every day I do atleast a 20 minute workout along with other random workouts on skimble. They have Zumba for xbox, wii or ps3. The wii and xbox also has three other zumba games.