I love this tutorial by ohdeeoh on turning old paperbacks into custom hardbacks. I'm sure there's a number of titles in my bookshelves that could do with a loving revamp. And how lovely would custom covers be when you find a sad copy of an excellent book at the white elephant stall on the weekend?
I'd love to get my genius artist brother to draw illustrations for worn out books and recover them as gifts, that'd be wonderful. Ooh the blogosphere is so full of good ideas!