Don't know if this is of any use to anyone but I found a site selling diodes at these wavelengths:
Re Diodes 635 & 639 & 640 & 642
Top power is 150mw but given that at 642 I think thats approx 400mw equivalent to 660nm I thought it might be of interest.
http://www.photonic-products.com/pro...i_visible.html