There are some fantastic examples here http://oddee.com/item_96527.aspx What others are worth mentioning. My favorite that I've actually studied in is New College, University of Edinburgh I loved having classes in the little rooms in that building and their was something about the stacks in the basement that made me feel scholarly.
perhaps not in the same vein but here's our main municipal library. the silo you see in the back is 17 stories tall. all very 70's but what's notable is not the building but the collection: over 3 million pieces, more than half older than the US constitution and several thousand from before columbus discovered america. you can't display that kind of stuff the way they do at trinity or coimbra. i'll make sure to check out new college though, that's where we're headed this summer.
Always been a fan of Lou Kahn, maybe because he's one of Philly's finest. That said, his Exeter Library gets 2 thumbs up from moi.
If in Edinburgh, Old College is probably actually more impressive, but you'll go right by New College if you take the back way up from the Castle to the Royal Mile.