I'd say I have a fair amount of shoes for someone in my demographic; probably a few dozen, including flip flops. I quickly found that my not-so-big Chicago apartment closet wasn't built for housing the modern gal's shoe collection, so I found a solution: The Shoe Wheel.
This miraculous contraption is a mobile storage unit with 20 pockets that can be expanded or contracted to fit anything from sandles to stilettos without squashing them. It's on wheels, so you can pull it in and out of your closet, and it comes in a variety of colors. I personally leave it on display in my bedroom because it's just that cool.
The wheel costs $65, but if that's to steep for you - or you feel you wouldn't use all the pockets - you can try the Shoe Pod. It's also on wheels and has 12 expandable pockets.
One warning: it's a BITCH to put together. But it's completely worth it.