(Click on picture to see a larger image of Madan Mohan.)
"Krishna is known as Madana-mohana because He conquers the mind of Cupid. He is also known as Madana-mohana due to His accepting the devotional service of the damsels of Vraja and rendering favors unto them. After conquering Cupid's pride, the Lord engages in the rasa dance as the new Cupid. He is also known as Madana-mohana because of His ability to conquer the minds of women with His five arrows called form, taste, smell, sound and touch. The pearls of the necklace which hangs about the neck of Krishna are as white as ducks, and the peacock feather which decorates His head is colored like a rainbow. His yellow garment is like lightning in the sky, and Krishna Himself is like the newly arrived clouds. The gopis are like footbells on His feet, and when the cloud pours rain on the grains in the field, it appears that Krishna is nourishing the hearts of the gopis by calling down His pastime rain of mercy. Indeed, ducks fly in the sky during the rainy season, and rainbows can also be seen at that time. Krishna freely moves amongst His friends as a cowherd boy in Vrindavana, and when He plays His flute, all living creatures, mobile and immobile, become overwhelmed with ecstasy. They quiver, and tears flow from their eyes. Of Krishna's various opulences, His conjugal love is the summit. He is the master of all riches, all strength, all fame, all beauty, all knowledge and all renunciation, and out of these, His perfect beauty is His conjugal attraction. The form of Krishna, the conjugal beauty, is eternally existent in Krishna alone, whereas His other opulences are present in His Narayana form."
(Teachings of Lord Caitanya, Chapter 10)
*Special thanks to Anandamaya das for his classic photo of Madan Mohan.