In XE2 there is a new function : 'styles', for VCL(.vsf) and Firemonkey (.styles), and some are provided in C:\Program Files\Embarcadero\RAD Studio\9.0\Redist\styles directory.
As it seems to be easy to create a new style, is there any 'styles Gallery' Web site or blog somewhere ?
No, for the moment there is no such thing like a gallery of styles for FireMonkey or VCL styles. But if you want to create you own try these entries in my blog which show an easy way to create/modify new VCL styles and FireMoney styles in few clicks. Both articles include additional styles to download.