What are your favourite examples thereof? Mine are French champagne, from the very beginning, at this moment in time, added bonus and free gift. I'm not sure if the following are tautological strictly speaking but, either way, are curious: PIN Number, ATM Machine, FHM Magazine, LCD Display and LAN Network.
My pet hate is "repeat again" when someone actually just means "repeat". A friend who lived in Italy for a while is still haunted by "The La Scala opera house". PEDANTS OF THE WORLD UNITE!
If tautology is defined as saying the same thing more than once, my least favourite is "tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks tuck your blanks into your blanks"
Another one heard occasionally is where people try to show off and start a phrase with "whence" and end it with "from", e.g. "go back to whence it came from".