Y'know what one of the most amazing examples of visual effects I've ever seen is?
Zodiac
There's this scene where Mark Ruffalo is walking around a San Francisco crime scene at night, on some Haight-Ashbury-esque street.
Just about everything surrounding him, from the moving cars to the houses, was put in via cgi. I had absolutely no idea it was all fake until someone brought it up on a message board I frequent.
http://www.youtube.com/watch?v=TT491ctM8Kk
I've been wanting to start a thread about this for a while, but this is proof that Dave Fincher (a former ILM-er!) would've been a perfect director for one of the prequels.