Interest checks are basically watered down and cannibalized sections of my OOC that I post after my OOC is already up. It has flavour text that has a hook, a summary about what the game and story are about, and the standards and explanations that don't fit into a summary.

I just format it like my OOC, use graphics and colour the headers and boom, you have a functional interest check that primes people into the gist of the RP itself.