Advertise anything as long as it follows the Scratch guidelines. Have fun, but please do not spam. You can also chat, and - F4F? Sure, but just don't ask me; I don't do F4F. Have fun!
There aren't many credits, but here you go: The Scratch cat head is the default sprite—everything else I made (except for the screenshot of the Green Flag) Also, the things listed on the poster are some of my projects. If they sound interesting, they are all on my account.