I know a lot of webcomics creators are fans of Steve Jackson Games. Steve Jackson Games is holding a month-long contest for webcomics that refer to their Munchkin game. At the end of the contest, the SJ Games Men in Black will vote on the winners. Some nice prizes for this — $1,000 first prize, $500 second prize, $200 third prize, and some honorable mentions which will win your choice of Munchkin core sets.
The contest begins on May 1, 2011 and ends on June 1, 2011. To enter the contest, send a link to your webcomic to email@example.com. The link should be to the page on which the comic appears, not just your home page. The e-mail entry must be sent to SJ Games by noon (Austin time) on June 1, 2011. Please include your name, address, and e-mail address.
Lots more details at their website.