NASCAR - the first dozen or so Spint Cup races of the season are on Fox, the next dozen on TNT, the third dozen on ESPN, and the last dozen (or so) are on ABC. If a race is rain delayed or postponed (which happened a lot this year) it may be broadcast on TNT/ESPN/ESPN2 instead of Fox/ABC.
This year TSN picked up the TNT/ESPN broadcasts; and the two which were on TSN2 came during the free preview. In the past SPEED (Canada) has also shown the Cup races. (SPEED also has lots of pre/post-race coverage.) Practice, qualifying and the Nationwide and Truck races are sometimes broadcast, sometimes not (or are tape delayed until middle of the night or middle of the week).