If you're feeling a bit bored reading the same old authors and wonder what else is out there, try out the Literature Map. I've been playing with it for hours! Yes, it could do with a little tweaking (some author's name appear twice for example, and some more recent writers haven't been included yet) but I've got some pretty useful suggestions from it.
Also useful on the same site is Gnod: type in the names of your three favourite authors and the search engine will suggest another author you will enjoy. I typed in Atwood, Proulx and Rohinton Mistry, and received the suggestion Vikram Seth, which I thought was pretty good.