I don't know if there is a site just like gamiss but if you want to buy clothes with bitcoin you must exchange it first to $ and paypal as a payment method. Because most of the online shops do only accepts payment with paypal or any other authorized web site. If you are not unable to find some other site like this, well try my suggestion and use virwox for it.
I also dont know if theres a site that you could use the bitcoin to some stuff and clothes. In addition to that, I think if you want to buy clothes by using bitcoin I guess you need to convert it into fiat. I think there are some sites that already accept the bitcoin as a payment of their costumer. I hope bitcoin will consider as real money and you can use it even in the things that you want.