mctrivia: I just went to a profile of someone with 1700 games - the page showing his games is currently 552kb large. An image tag of <img src="/images/dot.gif"> clocks in at 27 bytes. Even if said person would have half of his games with a message left by his opponent (which seems quite unlikely, he would have to have multiple conversations going on with the same person), the pagesize would increase to 575kb. Big deal. An increase of about 23 kb, slightly more than the size of the dragon image, and significantly less than the latest smiley added.

But I wouldn't like the lone '*', as it cannot be surpressed with a style sheet. <span class = 'message-indicator'>*</span> could handle that, but then you might as well use an image.