A cracked tile floor is invariably a cracked concrete floor that has telegraphed through to the tile. There are several ways of handling this, the best way being to remove all of the cracked tiles plus an additional row on each side of the cracked tiles. Completely clean the concrete floor, exposing the crack underneath the tile. Most professional floor covering wholesalers and retailers carry a floating bitumen membrane (usually 6″-8″ wide, sometimes 12″ wide) that you apply over the top of the crack. It serves as a cushion and shock absorber between the tile and the crack itself. Then you simply re-spread your thin set mastic and relay your tile and grout as usual. This process has a much better success ratio in solving the cracked tile problem than other options you may be tempted to try.
If you have chipped tiles any good epoxy glue type product will repair ceramic or saltillo tile (if you have the chip). However, refinishing the surface to match the original tile is the tough part. I have talked to people who have used a similar color of auto body paint to make the blemish disappear. ###