While browsing on slow internet at another person's house, there was a little bit of lag when I clicked on the site switcher. It was enough to trigger the tooltip. What it read surprised me:
A list of all 233 Stack Exchange Sites
But wait... don't we only have 117 sites? I'd imagine that this is a simple bug, but it's very misleading. Another thing I noticed while investigating is all the other site switchers have 119 sites on the tooltip. I haven't actually counted.
Why hasn't this been fixed? 233 is with metas, 117 is sites, and 119 is sites with A51/StackApps/Careers 2.0 (not sure which isn't counted). I'm changing this to a feature-request.
Change the site switcher on the main page to 119 and then change the 117 quote to this:
That would clarify it a lot. We don't really need the 233 number, especially since not all metas show up on the site switcher.