Shit loads of everything.
Everything. Got books everywhere and spend loads of time in the library, re-read shit loads too.
By the way Op, which Russian classics are you talking about? I've read a few of Chekov's shorts which were great but not many others. I have yet to pick up a copy of War and Peace.
For authors which Escapians might not have heard of but need to read there's Phillip K. Dick, apart from his science fiction stuff you really need to check out his masterpiece Valis. Seriously.
Also Robert Rankin for an author on par with Pratchett, George Macdonald Fraser for history/comedy (better I think then anything Cornwall has spewed out, damn I love Sharpe) and for that matter Woodhouse must be read. Ah yeah J.k Jerome's Three Men In A Boat is great.
Jules Vernes stuff is good but bored me a bit as for those who might not read Twain, check out a Conneticut Yankee in King Arthur's Court. For all intents and purposes a political commentary alike Animal Farm wrapped in a time travelling fantasy adventure.
H.G Well's is the daddy of scifi for a reason, for those who've read modern classics and like Gemmel/Feist/Asimov/Adams check him out. Just.... I don't know, maybe you'll come to like the drawn out descriptions of everything.
Also check out a good translation of Don Quioxte, it's really worth reading (make sure you get one that gets the humour down right.) Also the Three Musketeers, Man in the Iron Mask, well anything by Dumas. Really. He was an arrogant prick but a god with a quill, best of his age if any.
Jesus there's really too many now that I think about it, there's too many...... argh AGrGh the weight of literature....!