In a display of honesty that goes some way toward improving the reputation of his colleagues, an Athens cabbie has returned an Olympic medal left behind in his taxi by a Dutch athlete. A spokesman for the Athens 2004 Organizing Committee said taxi-driver Ioannis Zavos found Diederik Simon's lost silver medal - which he won on Sunday with the Netherlands' eight rowing team - on Monday night, and handed it over to the cabbies' union. Simon, who had contacted Athens 2004 officials in despair, was to get the medal back later yesterday. Zavos said he had taken Simon from the center of Athens to a destination on coastal Poseidonos Avenue. «I was cleaning the car on Monday night, and found a little bag with the medal in it,» he said yesterday. «I never even considered keeping it. I thought of the young man who had won it, and how he would return to his country [empty-handed].» Government spokesman Theodoros Roussopoulos and Athens 2004 praised Zavos for his deed.