I'd Remove the wood paneling from my 2600 and replace it with chrome. :)

Maybe a black Wii.....

360: White with a blue light instead of green (but since green is the official color of Xbox.....).
PS3: Flat on top instead of curved. A different font, and no colorful PS logo on the front.
Wii: Looks very plain, horizontally. That's why I bought a horizontal stand for it.

I'd make the Wii's disk drive quieter. For some reason Nintendo games don't spin the drive in a way to make the drive loud but third party games do.

I'd also make the Wii just slightly smaller (Maybe shave 1/4 the size off it) ;)

that looks like a ps2.

for my ps3 i would like a slim version like the ps2.

Get rid of the piano black finish on my ps3. Fingerprints on it drive me CRAZY. Micro scratches are easy to spot on it.

Anything besides the current finish that is easier to maintain.

PS3 - White shiny finish
360 - Smaller, slimmer
Wii - Black shiny finish

id like my ps3 to have a pure silver finish :) not gold that's a bit too far :P

What about a can holder for your fosters?

Reminds me of when CD players first came out for computers and that some people thought they were cup holders.