
Dishliquid |

For starters, a PDF of the Rise of the Runelords Player's Guide can be downloaded for free.
It has high res maps of Sandpoint and Varisia.
Beyond that, I consider the forums to be a huge resource. There are multiple, searchable threads that are full of player-generated resources, including erotic Nualia art from Tsuto's notebook, Swallowtail Festival speeches, bonus encounters, and DM shop-talk.
Also, check out the PbP forums (especially this one) to get a sense of Sandpoint as a living, breathing community, not to mention seeing how the DMs are running combat.
As far as other official resources, I'm not really sure if there are any. Then again, I don't recall seeing any promise of online content in Burnt Offerings...
I'll be running the first session this friday, but the past few days of perusing the forums have made me 1000 times more prepared to run the module. I pity the alternate-reality-me that didn't think to check out Paizo's forums.
/Paizo fanboyism