Legal (Baen allows nonprofit sharing of the cd's) Baen books from the cd's included in some hc's (currently 9, with 2 more to come in 2007). I do not know if the link was previously posted but it's very useful (not to be confused with the Baen free library, here there are full series to the given point of publication)
http://baencd.thefifthimperium.com/
Liviu