A couple of these are just jokes and not really playable, but they make for some pretty cool screenies if there's lots of action going on when you spectate.
Decide for yourself which ones you think are playable.
Download the files to Defcon\data\styles and they should work right away (after you've loaded them, of course

I personally use Purple Haze, as it resembles the map in Mars Attacks!, well slightly.
EDIT: Shinygerbil has been so kind to packaged them up in a RAR file:
http://www.shinygerbil.co.uk/files/Styl ... ligula.rar
NOTE: I have smooth lines disabled, as the look is somewhat crisper, but do as you please.
Enjoy!:
1000_Rivers_of_Powdered_Blood:
http://www.mediafire.com/?2yiwyhy4ymh

Algae_Invasion
http://www.mediafire.com/?bm00zuzlmhu

Atomic_Winter
http://www.mediafire.com/?7ajyaay1nbn

Big_Freeze
http://www.mediafire.com/?8hdlncnnmjd

Blood_Tears
http://www.mediafire.com/?bkzktiwnumw

Everything_to_the_MAX
http://www.mediafire.com/?0nyyytm3gtz

Evil_Earth
http://www.mediafire.com/?afyd33meywj

Golden_Glow
http://www.mediafire.com/?atnz0lmv2iz

Ghost_Mist
http://www.mediafire.com/?8neeyzykde4

Invisible..
http://www.mediafire.com/?60jmxmt4gkn

Kitsch_Armageddon
http://www.mediafire.com/?brzzgzuxumt

Last_Sunset_On_Earth
http://www.mediafire.com/?fyqmot2myun

My_Eyes_Hurt
http://www.mediafire.com/?ddywoq2fxjj

Night_vision
http://www.mediafire.com/?c1nnidnwtzy

Purple_Haze
http://www.mediafire.com/?5ohjzzgdmtn

Strictly_Retro
http://www.mediafire.com/?2nznlmndg4z

Slightly unrelated, but I have also added my ballistics chart to the Strategical forum:
http://forums.introversion.co.uk/defcon/viewtopic.php?t=4073