If you want to decorate your kid's wall or even add some fun images to your man cave you can create your own fabric wall decals easily and inexpensively using cotton fabric, iron-on adhesive sheets and a clothing iron.
Crafting weblog Made by Marzipan shares this technique for making your own fabric wall decals: Iron your fabric so that it is completely wrinkle-free then lay the fabric face down and lay down your iron-on adhesive sheet (the author specifically recommends Heat n Bond as the adhesive layer is thicker and less likely to leave residue on your wall) and iron the paper of the adhesive sheet so that the adhesive bonds to the fabric. When that cools down you can cut out your design by freehand or by using a stencil -- remember that you are cutting out the reverse side of the image.
At this point you'll have a decal that can be ironed directly on the wall; this will heat up the adhesive so it sticks well to the wall and after the adhesive cools it should be relatively easy to pull off when you need to remove the decal.
Fabric Wall Decals [Made by Marzipan]