H&M has opened online stores for the UK as well as Austria, Denmark, Finland, Germany, Holland, Norway and Sweden. You can find the online store at shop.hm.com. There is no U.S. online store yet from H&M.
The online store sells men's, women's and children's fashions and accessories. H&M's UK online store is also selling cosmetics, bedding and linens. The website is offered in both flash and html versions. The online store is very fast. One of the features missing, as Econsultancy notes, is a search box.