When Aidyn was about that age I used to lie next to him on my bed and stroke his face until he went to sleep... I remember it working quite often... though I dont know if its suitable for someone else to do (lying on the bed), but the face stroking may work.

If he is going to daycare, the women there will usually be pretty skilled at settling babies down... at our daycare they will sit there next to the cots and pat them to sleep, and if they are crying they will pick them up and cuddle/rock them....