Ran across this interesting article from IBM. Seven tricks that Web users don't know is about what designers and developers can take for granted when creating a website. Read the article, but for the skimmer, the 7 items that are explained are:
# Logos that link to the home page
# Concepts of security vs. privacy
# Rollover menus
# Arrow keys and drop-down lists
# Navigation by hacking URLs
# Knowledge of browser controls
# Second browser windows
Now remember that this article was done in 2001. I'd be interested to see how much of it applies nowadays, as people become more accustomed and trained in the ways of the browser. But then again, you never know. These are just some interesting thinking points for the next time you take something for granted.