There's lots of information, screenshots, and a video interview with the developers of Bioshock 2 (including footage of a Big Sister in action) here.
If you still haven't seen it, here's the fabulous opening to Bioshock:
And here's a cinematic encounter with a Big Daddy:
*Previously: Homemade Big Daddy toy.
*Would you kindly buy Bioshock toys at eBay.