Spare a recommendation or two?

I've recently decided that I'd like to get into the sci-fi genre - I like Star Trek enough that it should be a good roll. I've gotten my hands on the Star Wars novel adaptions, and based on the suggestions of my friends who enjoy reading, I've got Dune, Do Androids Dream Of Electric Sheep?, War Of The Worlds, A Princess Of Mars and The Outlaw Of Torn.

I'm rustling through the sci-fi tag for this community at the moment, but can you folk recommend me any other sci-fi books that I should get my hands on? I'm not too fussy - it's going to be my first foray into the genre, so I'm willing to give any sub-genres of sci-fi a go. c: