Best ab exercises for post-baby flab?

Having a firm mid section comes from low body fat and adequate lean mass. Rather than doing ab exercises it's a good idea to incorporate some sort of resistance training/lifting program that works all body parts through the week.

http://community.myfitnesspal.com/en/discussion/10332083/which-lifting-program-is-the-best-for-you#latest

Also, google diastasis recti - when you're pregnant your abs separate and often don't come back together without help. Many regular ab exercises, such as crunches and planks, will make the problem worse but there are others that help.