I like to make logos/banners for AAGH Games entries into Ludum Dare, and for the last two we've entered (Ludum Dare 39 and the upcoming one) I made the logo using our pictures of our entries to date in the words "Ludum Dare" plus the number. Here's the one I made for Ludum Dare 41, for example.

I like the way it turned out, and it works well because we've entered 10 Ludum dares prior to this, making this our 11th. That means it fits cleanly into the logo.

How I'm going to handle this as our logo for Ludum Dare 43 this winter, though, is anyone's guess. 😄