Organizing patterns

I have got to come up with a way of organizing my knit and crochet patterns. I've got patterns in magazines and books. Those are organized automatically by being entered in my Ravelry library. The problem's with the pdf/computer patterns and the miscellaneous paper patterns. I bought a duplicate pattern yesterday, which annoys me no end. Some of the pdfs are stored in my Ravelry library. Some are stored on my computer in the directory where they are meant to go. Some are printed out. Some are in all three places. Some are in none of these places.

Sounds like time to build a simple little database. Now if I could only remember to check it before I buy something, that would help.