After the implementation of the new summoner icons, most of which people switched to immediately after they found out about them, I had an idea that might just bring some attention to something juuuust a notch above the upcoming championship:
Breast cancer.
So here's the pitch: Implement a new pink ribbon icon, and for every user that uses it during that week/month or whatever duration is decided upon, Riot donates x amount of money towards a charity of their choice. Not only would it raise awareness as Riot could follow up with numerous links and whatnot in the announcement/conclusion notes, but it'll also be great PR.
Going by the majority of splash arts for our various champions, it's rather obvious that Riot has an invested interest in breasts, so step it up!