It looks like this has been possible since, oh, Mac OS X 10.5 or so, but I hadn’t come across it before. I’m guessing that might mean some of you haven’t, either.
If you’re one of those amazing folks who have seen this already, then feel free to check out all our other OS X tips; it’s possible there’s something in the list you didn’t know about already.
For the rest of you, if you want to disable the translucent menu bar on your Mac, it’s relatively simple. Check it out.