I think one essential aspect of selling on the internet is monitor calibration. There is no real standard for calibration and I would think the general public just uses factory settings or adjusts to their own comfort level. Where as do photographers and website developers calibrate to the same standard?
Video cards, crt vs lcd, older model pc's, size of jpeg files, will all effect how photographs are seen on a pc from the internet and influence whether or not they will buy. I have a monitor calibration page on my website and I see others have the same. But I wonder just how effectvie it is.