I've found a couple of things that aren't working as they should be while surfing around.
Both of these happen on Facebook.
On your main profile page, clicking the quick links works, but the blue highlight doesn't move along with the selection you've made.
When viewing a friend's photos, clicking on the paging links doesn't do anything except refreshing the page. The same goes for the list of galleries. However, when you click on one of the galleries to view it, paging does work although the whole page refreshes, which isn't very Web 2.0-like. In FF and IE, only the images are refreshed and not the whole page.
The last thing I found was that Java Applets aren't working, which means I can't use homebanking. This isn't really a bug (there's just no plugin for it yet), although it's a bit irritating.
I'll update this page if I find anything else.