It wasn't colours I was referring to, sorry.
What I meant by skins is a different appearance of the mirc window itself, eg some software let you choose woodgrain, sleek metalic look, rusted metal look, etc etc.
My gf's brother even has a "catwoman" skin for his window's media player, which opens like a cats eye when you first open it, blinks once, and then the buttons appear for you to play music.
Like I said. It's not something I would use personally, but I know is something that would be used by many if added. Every now and again you get people asking in forums "how can I change the appearance of my mirc buttons?"
People like to personalize stuff these days.