Indexing the 1940 census is even more fun in a group and with in-person tech support! I just finished indexing two batches of the census at the 1940 Census booth in the NGS 2012 conference exhibit hall, and it was really nice to be able to ask the person sitting next to me "is that an L or an F?". It was also nice to be able to raise my hand and ask an expert how to handle unusual situations...and even though I've indexed several batches, I still encounter things not included in the instructions. If you're at the conference, I suggest you take a shift at the booth even if you don't want the shirt.
I hope they announce at the end of the conference how many batches they think got indexed here...they've got a dozen computers and I have yet to pass the booth without seeing a line of indexers-to-be.