This Wikipedia site provides definitions and descriptions of different sand dune types.
http://en.wikipedia.org/wiki/Dune
This Wikipedia site discusses the many aspects of sand dune stabilization.
http://en.wikipedia.org/wiki/Sand_dune_stabilization
This site, sponsored by SaharaSafaris, is a good general information site and also provides the Arabic names of the several dune types.
http://www.saharasafaris.org/sand-dunes
This site, sponsored by the U.S. Geologic Survey, defines and describes five basic types of dunes: crescentic, linear, star, dome, and parabolic. Satellite photos of each type are included.
http://pubs.usgs.gov/gip/deserts/dunes/
This site, sponsored by Edumedia, presents an animation of the behavior of sand dunes.
http://www.edumedia-sciences.com/en/a634-sand-dunes
This site, provided by the faculty of King Saud University, presents the abstract of a paper studying the control of the sand flow field around a specific dune, the Barchan Sand Dune
http://faculty.ksu.edu.sa/ASHIBL/Pages/SandDune.aspx