When they all become available in ebooks or if you don't mind reading most of them in pbooks, I heartily and highly recommend Ursula K. Le Guin's Hainish Cycle novels. They are all quite good. Here is a link to a wikipedia article that will give you some good background information on the novels:
http://en.wikipedia.org/wiki/Hainish_Cycle
They should be read in the following order:
Rocannon's World, 1966
Planet of Exile, 1966
City of Illusions, 1967
The Left Hand of Darkness, 1969 (winner of the Hugo Award, 1969[21] and Nebula Award, 1970[22])
The Dispossessed: An Ambiguous Utopia, 1974 (Nebula Award winner, 1974[23]; Hugo and Locus Awards winner, 1975[24])
The Word for World is Forest, 1976 (winner of the Hugo Award for best novella)
Four Ways to Forgiveness, 1995 (Four Stories of the Ekumen)
The Telling, 2000 (Locus SF Award winner, 2001[25]; Endeavour Award winner
BTW the first three novels are usually published in a omnibus edition. If memory serves me correctly (they are packed away in box somewhere) it is a Sci-Fi Book Club edition.