Some names I can think of is Ian Thorpe, Michael Phelps, Kieran Perkins, Grant Hackett, That russian bloke umm...Alexander Popov (that's the one haha), Pieter Van Den Hoogenband (or Hoogie).
It would be a sick race, to see Hoogie, Phelps and Thorpe in the pool at their best. I reckon all three could potentially break the olympic/world record finishes.