I do the same thing with the library..... there are so many great books in the library and usually I just scan the pages into my computer and i have a folder that are just for ideas and recipes on my server at work.
less paper for me the better. (although at times I do make a copy when i need it)
The one I reach for the most is The Cake Bible by Rose Levy Berenbaum, because she's so scientific about her cakes. It's really interesting to me to read why you don't double the amount of baking powder when you're doubling a recipe, or why beating the flour into the butter prior to adding eggs builds a different crumb to a cake.
I also like Dede Wilson's The Wedding Cake Book for different cake flavors/recipes.