Mentor, mentor, mentor especially if you have fellow work mates that even express a slight interest in commuting to work. Offer to ride with them, fix up there bike so that it fits them (another reason why people dont ride, they are not comfortable) but above all lead by example.
We have locally just run a BikeTrain or otherwise called a BikeBus. It is a scheduled timetabled route for prospective cycle commuters to join providing the moral and physical security that novive rides need. All the while the leaders or 'drivers' can give a running commentary on how to handle the traffic and avoid hazards. For more info visit www.cyclingsouth.org or http://galifrey.triode.net.au/bikebus/index.shtml
Go For It
Tim.