If not an online catalog, do you use any other method to catalog your book collection? Excel spreadsheets, index cards, a notebook, anything?
Until March of this year I was an old fashioned kinda girl and kept my list of books I've read in a word document. It worked for me and I never really questioned my methods until I came across Librarything and saw the light. I found my people! There are others in the world (virtual) just like me! Those I spend time with everyday at work and home don't understand me :-(. Aha, but those on LT do and it's comforting to know that there are others just as book crazy and outta control as my hubby swears I am when he sees the TBR piles growing, not shrinking. Just try explaining to a non-book obsessed person why you must be surrounded by those TBR piles and their eyes glaze over and the attention span becomes that of a gnat.
For those of us obsessed with everything books this is a god-send, the best thing next to sliced white bread and all those other cliches. Now I not only obsess about my books but I get the pleasure of obsessing about what others in the LT community are reading, talking about and doing. This year LT did "SantaThing Secret Santa". I signed up and now have the pleasure of buying book or two for someone who will truly appreciate the gift they receive.