5. Over-the-door shoe bags (or pocket organizers) - which could be hung other places, too.
The Container Store and Organize-It have a number of options. Room It Up has some for those who prefer patterns. In the UK, Cath Kidston has a pretty hanging shoe tidy, shown above. Update on Sept. 28, 2009: The Cath Kidston web site is now show a different shoe tidy - Regal Rose.