i use an excel spreadsheet that i download to my ipaq. i then take my ipaq with me when i go shopping for cd's and albums (a couple times a week) to verify if i have the album/cd or not before purchasing. I also have a list of music that i want to purchase, so if i see it, i buy it. the columns in the spreadsheet are: artist, album/cd name, type of music (jazz, new age, rck, etc..), and format (cd,sacd,album,dvd). another plus, i can sort by any column to find something fast.