I used it for over a year on yellow, but now its red.

Yellow in case I get messages from my friends.

how do you put it on standby?

WiiConnect24 enabled, so yellow.

Yellow light.

It gets warm. But it works fine.

Mike from Morgantown

Hold down the power button for five seconds or so: it'll turn red.

'Course, you're better off just turning the whole thing off at that point...

On topic, I used to unplug it, but now my new recharger uses the Wii's USB port, so yellow light if I've been playing during the day (I usually am now).

I leave red light because I heard that some of the early Wiis don't do well when they are left on stand by (yellow light).

always left it on standby, and mine is a launch one.
didn't have any problems so far.

mine isn't launch, it is black friday so close enough. And always yellow for me as well.

Well unless I move my Wii, then sometimes too lazy for a while to reconnect to the internet. I don't really ever play online so dont' really care.

Red or unplugged. Depends if I'm lazy or not (usually am). I used to leave it on standby, until it got hot one night. So I decided to not take any risks and turn it off.