So I just got a letter from the US Census Bureau that I need to take the "ACS Survey"....wTF is this? Has anybody taken it?

When you respond make sure you give them your full legal name, social security number, and credit card information. </sarcasm>

A quick Google search gave me this site http://www.census.gov/acs/www/index.html so it appears to be real. I've not received one, but that should help you decide if you want to fill it out or not.

Actually I had to call a lady, who now has to call me back, to arrange something or other.

This is starting to sound like a big PITA

The Census has long overstepped it's bounds. The Constitution says take a census (as in just count how many people there are). They take it to mean they can take all the personal info they want.