Stilly - thank you for that sage advice about flicking through books - I made a start on my bookshelves this morning and managed to find an address that I've been looking for for 2 years! Luckily the chap still lives there so I can send him his 2 years worth of greetings cards!
There's a whole bin bag of books waiting to go to a loving home now... duplicates mostly, out of date self help books and a pile of SciFi/TV books I've not read for 10 years and not likely to read again.... Now all I need to do is actually remove the bag before I give in to the temptation to double check them all again....