This is a real shame, I really liked Shelfie. I remember seeing it on the Dragon's Den and thinking I needed to download it right now! Sure, I probably didn't use it as much as I thought I would, but... that's a moot point now.
It ceased operating on January 31, but you can still retrieve your data up until February 28th.
Too bad. Hopefully they're on to bigger and better things. Best of luck!