We all need structure and I think I need it more than others thanks to my restless scatterbrain. I started adding things to my catalogue and must have been at least 3 or 4 books in before I'd actually worked out how librarything could be most useful to me - pending/unfinished reading lists controlled with tags. I can syphon off groups using combinations of tags: nonfiction, philosophy, unfinished (for when I'm feeling serious); or fiction, humour, unread (for when I'm not).
A great idea that can surely only get better, go and take a look.
1. This is just some of the tools I use, not an attempt at a comprehensive list.
2. incredibly, I almost forgot this one, thanks to John Hill for reminding me in the comments about the tool I use every day.