I'm all about combining different uses in one room but I've never seen a combination library/bathroom. I'm a big bathtub reader myself. I've never been one for reading on the toilet but to each his own.
When I feel the urge to do any of the various things that propel me toward the bathroom I really only have one thought: "I wish my toilet had more bling. Then _-ing wouldn't be so frightfully tediious."