The thing I have always loved most about the Internet is the way it can be a great equalizer. One person with a good idea can reach masses they would never be able to by traditional physical means.
And here's one great idea. https://haveibeenpwned.com/
With the ever increasing number of hacks and privacy breaches threatening all of our personal information... One persons solution? A tool that allows you to search disclosed data dumps to find out if your account is on the list and where or how it might have come to be there.
It doesn't matter if the leak is anywhere from Adobe to YouPorn (that's almost A to Z!) - you can check your account or with a couple extra steps your entire domain (if you control it) at https://haveibeenpwned.com/DomainSearch.
With so many hackers are attacking so many companies and stealing so much data... One person created a tool to let millions of us know that we really need to update those outdated passwords. Really.
Simple. Elegant. Kudos. :-) This system is even being integrated into other tools now which will make the Internet safer for all.
PS. This does take Troy Hunt a lot of time to maintain and does cost him money. Sure he's made a mark on the Internet - but he will accept donations... https://haveibeenpwned.com/Donate