Open comments in new window icon
It's a 14x12 4K PNG with a transparent background that looks OK on most colors (it was designed for a white background).
Here's what it looks like in context:
The icon was inspired by the "New Window" QBullet, but is a lot simpler.
You can use this on your site if you like. I place this icon in the public domain.
Update: Uh, I guess IE 6 doesn't support transparent PNGs. So if you want to use this on a colored background, convert it to a GIF.