Nature had some interesting articles on incentives for development and distribution of and access to drugs for neglected diseases in a recent edition. See in particular:
Neglected Diseases: At what price? by Patricia M. Danzon
Neglected Diseases: The road to recovery by Carlos M. Morel et al
Neglected Diseases: Patent sense by Paul Herrling
Thanks to Thiru Balasubramaniam via the A2K list for the pointer.