carnofago, I just installed the Custom Colours Mod thingy, and is there a way to make a standard colour for the username?
The Black blends in a little TO well to the background
I'm not sure if theres is any easier way, but the custom colour for each user is stored in the Database and it's default attribute is set to NULL, so the only thing you need to do is connect to your MySQL database and change the default attribute for the hex code of the colour that you would like to be the default
for example here we are gonna change the default username to black so unless anyone change their username colour it'll be black
ALTER TABLE `phpbb_users` CHANGE `user_custom_color` `user_custom_color` VARCHAR(6) DEFAULT '000000'
(I really hope that was what you meaned with your question