The Foreigner series by C.J. Cherryh follows a human ambassador for a group of humans trapped on an alien world. The novels deal heavily with a clash of two cultures that identify emotions and relationships in fundamentally different and incompatable ways. Deeply anthropological, the Foreigner series is fascinating and compelling, though occasionally hard to read due to the writing style.

Snow Crash is a strange cyberpunk style novel about a dystopian future. It is also one which has been profoundly influential in Sci-fi and on the computer using world. It is widely cosidered the general origin for the popular use of the word Avatar on the web. Snow crash is a deeply philosophical story about language and culture. It's also one of the most unique stories I've ever read.

Jack London? What does Jack London have to do with Sci-fi? Well, he wrote a story called The Red Plague about a plague wiping out humanity. Set in a future where only the brutal survived, the last surviver of the civilized world tells a group of boys about how it happened. A look into London's socialist beliefs, this is also a good yarn.

I've been a fan of Howard Tayler's Shlock Mercenary since about a year after he started the long running webcomic. The tale of a futuristic group of space mecenaries, Schlock Mercenary combines hard sci-fi with brilliant comic writing. "Under New Management" is the "dead trees" edition of the webcomic. It starts midway through the webcomic, but is a good place to start for the uninitiated.