MuralsForKids.com is an eCommerce site that sells all sorts of themed wall decorations mainly for kids, and are available in themes such as farm animals, tea party, or outer space, so whatever your child is up to, you are sure to find something here that s/he can be thrilled to receive.
Some of items on offer are made of paper, others of sticky material, and some others are hand-painted pieces that can be attached with Velcro, which in turn means that your children can draw and scratch without you fearing for your walls. But since not all is about kids, if you like floor to roof wall art, you can also get it from this store at very convenient prices and different sizes as well. Also cool about the site is that it provides very detailed installation instructions so that you can avoid calling in a fitter and thus same some extra bucks. Other children and general décor needs are also catered for at this site, like divine and cute switch plates, nightlights, rugs, pillows, pillow covers and other such menagerie for boys and girls. 
