The Bioshock 2 official site has been updated and now includes dollhouse-like vignettes. One panel includes a Little Sister doll and a piece of chalk that can be used to draw on another doll. I don't know if drawing something specific unlocks a secret.
Relatedly, you can find photos from New York's Splicer's Unite event at the Bioshock Facebook page.
*Previously: Video from the Splicer Unite event.
*Buy Bioshock toys at eBay.