I really like the J-Me metal shoe rack that works in the same way as this one, but I want a few of these and the J-Me ones cost 50 GBP each. Home made ones I've seen made with planks and shelf brackets all look a bit ugly, but using a few of these pre-shaped Ikea shelves is more aesthetically pleasing, uses fewer components, and costs about 8 GBP.
Stuff you will need:
Two Ikea Stripa shelves (About 4 pounds each)
Tools (not all shown)
SD card (or something of a similar width)
Pokey thing (Bradawl or thin screwdriver, for marking the wall through holes in the shelves)
NOTE: This is completely new, i built it hours before posting this instructable. For all i know, the toes of my shoes might warp after they've been in this for a long time. I take responsibility for my own shoes, but certainly not yours ;)
Step 1: Cut Shelf
I did this very quickly and dirtily, and it turned out well.
Mark a line to cut on the top shelf. I found an old SD card was just the right width. Clamp it, then cut that mofo!
Don't throw away the offcut, you'll be using it for something in a bit. See notes on the images if you're new to woodworking and need more details.
Step 2: Plane
The front of the shelf you cut off just happens to match the size of gap you need between the shelves on the wall (At least, that's the case for my - UK - size 9 and 1/2 shoes). Make some spacer blocks out of it, as shown in the pictures.
Step 3: Fix to Wall
I found it best to drill the wall and fix one end, then line it up to mark the other hole. Remember to always do it by eye - using a spirit level is precise, but, as I rediscovered while installing this, can lead to very wrong looking results if the floors in your house slope even a tiny bit.
Step 4: Enjoy Floaty Shoes
The shelves come with small metal pins and holes pre-drilled for joining them together at the ends, so you could easily run more than one of these along a wall. As it is, I find one of these can take three pairs comfortably, or seven shoes if they're crammed a bit.
Edit: Put a second one up, added some noisy phone camera shots to show it. The edge of the lens makes them look different, but both racks have exactly the same spacing.