For the record, this year's js13kGames [1] has just started days ago and will continue to run until September 13. :-)
It should be noted that most assets are still too large in this limit, so almost everything should be made from a code and many stuffs have to be consciously chosen to be included. For this reason, I feel that the limit is rather a very interesting threshold that allows for ordinary developers without much size optimization experience to start with, but should be plenty enough for experienced people to make difference.
With pixel art images however you can get a fair bit in if you're comfortable with low resolutions in 8bpp or lower.