I'm just curious about the meaning (or the origin) of some nicks, here there is a list (edited, thx to everybody for answers):

cooller ----> wrong (or right :] ) spelling of cooler; he used to read a magazine "Cool" back in his youth ages, and his nickname came from this interest
rapha ----> jehovah rapha "god of healing" or something
strenx ----> strength
zero4 ----> His favourite song is/was Zero by Smashing Pumpkins. It is the fourth track on the album
stermy ---> diminutive of exterminator in italian
k1llsen ---> former k1ller, but that nick was too martial; the suffix -sen after the kill means son
ischju ---> phonetic writing of issue
baksteen ---> "brick" in Dutch
krysa ---> means rat in Czech
p0ni ---> originally called phoenix
TOXJQ --->T O X Johan Quick
latrommi ---> reverted word "immortal
bpatela ---> (spells "bratela") - it's a slang form of a word "brother" in russian. so it's like "Bro"
pavel, arseny ---> just russian names
agentjkezoor ---> because name "agent" was always taken
ash ---> from the original evil dead, iirc. not from pokemon
ctapocta ---> starosta, spelled in latin with the same appearance like cyrillic. translated as head boy or elder. spoken like 'stah-ro-sta, not stah-'ro-sta
megbeguk ---> med-'ve-dik, a bear cub
lexaaa ---> 'lio-kha, from name aleksei
czm ---> crazyman
dkt ---> destrukt
vo0 ---> voodoo
Spart1e ---> from Spartacus
dahang ---> When you say "DAAAAAANG!" in the sense of wonderment or 'impressively surprised' (think "SHIIIIIIIT!"), then add just a little 'thug flavor' with the "H" sound, you get a tweaked, two-syllable idiomatic way of simply saying "DANG!" eh viola, DaHanG!
Sothis ---->another name for Sirius, the brightest visible star in the night sky
jewro ----> he says: "dont know where it came from other than my brain"
n0ns -----> from nonsense
Fraze, Camma ---> their first names: Frazer, Cameron
dem0n ---> "called myself raildemon for a short period of time because I liked the weapon. And then someone on a public server on dm6 asked me why I didn't just use 'demon' as my aim was kinda good overall and not just my rail.

av3k ---> ??
zsx ----> ??
cypher, evil

feel free to extend it