Let’s just get this out of the way: you shouldn’t upload other people’s stuff to the Internet. There’s no justification for it. It’s stealing.
That said, most people don’t pirate music, and most people used Megaupload, the precursor of Mega, not to give other people music but to back up their files at work somewhere easily accessible or put their vacation pictures somewhere they could easily grab them when wanted. So in that respect, Mega is as useful as it gets.
There are points about Mega which I am extremely skeptical of, like the claim that not even Mega knows what you’ve uploaded. I doubt titles of files are encrypted, guys. The fact that encryption can be turned off for certain users is also pretty lousy.
But as an actual service, Mega is pretty awesome. Essentially, all your files are encrypted locally before they’re uploaded, and only you have the key, and thus the ability to generate download links to the files you own.
This is useful for multiple reasons: it’s very secure, so you can use it without worrying about some random person downloading them. And it also has an excellent file manager on the site itself that’s simple to use. Basically, if you need to back something up, Mega will be a much better choice than almost everything out there.
Mega.co.nz [Official Site]