Danica McKellar broke a rib Thursday, April 24, while rehearsing for "Dancing with the Stars." The former "Wonder Years" actress tweeted to her over 90,000 Twitter followers: Hopefully, she and dance partner Val Chmerkovskiy can come up with a way to pull through together before Monday night's episode. McKellar is hardly the first "DWTS" contestant to get injured in a dancing-related accident. Last year, Bill Nye, The Science Guy, hurt his knee on the show. He uploaded a picture to Instagram...