This semester I was a GSI for two sections of Math 53 with Prof. John Neu: my sections were #107 from 12:10 to 1:00 on Mondays, Wednesdays, and Fridays, and #106 from 3:10 to 4:00 those same days. There was no general course webpage; this space is used for things specific to my sections (for enrollment questions, see the Head GSI's webpage here). In particular, I will post quizzes and worksheets handed out in class. Quizzes, worksheets, and answer keys are all PDFs. If you are on a Mac, these should open automatically; Windows users may need to download Adobe Reader if it is not already installed.
For posterity's sake, TeX sources for all files are available as a tarball here.