For the Sci-Fi lovers out there: Geek Exchange has some suggestions for you.
This one you're REALLY going to hate me for, but I don't even care! i09 has 10 Book Series So Addictive You Never Want Them To End. Yep, more series to your TBR. Sorry not sorry!
Have you read any of these series mentioned in the articles? Did I miss one you think I should add to the TBR? Let me know!