Most of my books have page numbers noted on the front page (in pencil!) that remind me of where my favorite quotes are. I also have loads dotted about in varies documents on my computer. I used to have a wall covered in typed out quotes I'd done on the computer and stuck up in my room! All on purple and lilac paper. I'm not sure if thats a bit mad.
I'm completely quote obsessed. Books, tv, films, songs, anywhere...