http://www.polycount.com/forum/showthread.php?t=110844 Its great for dropping basic textures, and place holders, if you want a complete asset I suggest you go over it by hand at the very least, but its great for prototyping things, probably more if you are better than me :)
RULES: This may seem like it's pretty complicated, and if you are starting out it can be overwhelming, so take it piece by piece. This can be broken down into a segments. Think about what will be unique, what will be tiled, what kinda textures you'll need to make, just plan before you go. All that matters is that you learn…
@Bonkahe: Slightly off-topic but you should try Opera as your Web browser and enable Turbo and it will compress the webpage before it gets delivered to you and lowers the download size of each page hopefully giving you a little more data each month spare. - http://www.opera.com/browser/turbo/
This is some amazing work! Do you mind showing how your doing your lighting? Maybe a screenshot of the editor to see where you have your environment probes, lights etc. Also, what console commands are you using to get such awesome shadows, global illumination etc? Your stuff is brilliant.