There's a long list of powered hubs that work and/or don't work at http://elinux.org/RPi_VerifiedPeripherals#Powered_USB_Hubs. They don't have a list of unpowered hubs -- you probably need to use a powered hub (that is, externally-powered) because RasPi's USB host ports source very limited current because of polyfuses F1 and F2. In some cases you can use a powered USB hub to power RasPi itself over a Micro USB cable, but it depends on the hub design.
