So i decided to give myself an avatar. 90x90 is a reasonable size, but under 6.00 KiB is nearly impossible lol. I started with this
a tiny 90x90 donnnie darko bunny head. but unfortunately it's 23.6KiBs so i had to make it smaller, after converting it to an interlaced png file, removing all background and shrinking it down it now looks like this 
lol so maybe a 30KiB avatar filesize limit would be slightly more reasonable, as is were kind of limited to about 15 pixels for png and jpg =)Edited it again to remove all color and darken it up and now it looks like this
Not as bad, but still a little too small.EDIT: ok after much much editing my 29th attempt made the avatar i have now that I'm actually quite happy with, weighing in at a whopping 5.57KiB, all i had to do was bump up the sharpness as much as possible =) Would still recommend making the filesize to at least 15 to 30, 6 is micro.