There'e so much that the internet is good for, a list of such would be both endless and silly. But one of the things that it's basic use for is, of course, information.
That's why I like sites like Ask Metafilter, and Yahoo! Answers, etc. And one of the more interesting takes on this is a site I just found (but which has been around for at least two years, it seems) is called I Did Not Know That Yesterday.
The current post there, for instance, explains why your fingers wrinkle if they are in the water for too long; another detailed why your nose runs when you eat spicy food.
This isn't rocket science, but in some ways it's sort of an explanation of science, and that's always cool.
Here's an example of a post I found particularly interesting, which sought to explain why blue jeans have that small pocket above the right hand pocket:
What's the purpose of the little pocket in the right front pocket of jeans?
The answer to this one is easy - or is it? -- coins. It has to be coins, right? I scoured dozens of online jeans listings. Pretty much every "classic five pocket design" boasted a coin pocket in the front right scoop pocket. Some of the coin pockets were exposed, some had flaps, some had insignias, but they were all described as coin pockets.
But then I stumbled onto a similar query on Ask MetaFilter and found the real answer -- watches. Back in the day before the wrist became multi-functional, folks carried pocket watches. These were fastened to the end of chains, and stored in special pockets woven into pants or vests.
Levi's 501s, originally introduced in 1890, featured watch pockets. And sure enough, after more snooping around, we found these vintage jeans from the 1970s listed as having "five pocket styling with watch pocket."
interestingly enough, in France it is referred at the "Zippo pocket" - one can only assume that could be a reason for the poor French time keeping, or a reason why they smoke so much.
For more on pockets and their uses, the BBC has a surprisingly interesting essay entitled A Very Brief History of the Pocket. And this Smithsonian piece details the evolution of pocket watches to wrist watches.
Anyhow, it's a good site worth perusing. It's going into the links on the right.