Make 2 macros, copy paste this into it.
/console overridefarclip 1
/console farclip 1600
/console horizonfarclip 6226
/console groundeffectdensity 256
/console groundeffectdist 140
/console smallcull 0
/console skycloudlod 3
/console extshadowquality 4
/console environmentDetail 2
Don't touch your video settings after this. If you do, you'll have to use the macros again.
Download this. It's the HDR mod - http://www.mediafire.com/?bjj5dtmbgm5
Unzip the archive right into your WoW folder. C:\Program Files\World of Warcraft\ by default. If you have a 64 bit computer it will be located in C:\Program Files (x86)\World of Warcraft\ by default.And that's it. The HDR mod will affect your interface as well, so whenever you need to look at the map or the dressing room, you can toggle it by pressing Shift+F12.
You can mess with the settings in the .ini if you want, it will change the effect of the mod. I'm pretty sure you can add godrays and depth of field, but I haven't checked it out yet. This also works with ANY DX9 capable game. So if you want to get these same effects in another game that you have, switch it to DX9 and put the mod into the game directory.