Mostly drugs, porn and cracked/hacked stuff. Some people say, you can even hire a gunman if you want someone dead but do not want yourself to end up in jail. (its probably bullshit, but sometimes i wonder what if its possible? not because i'm gonna use it ofc) That's why darkmarket/deepweb  really deserves its name.

I can find what i need %99 of the time with the help of google so, i really don't care about their stuff.

You should also take into consideration, whatever you download from the darkmarkets, can contain undetectable  virusses/trojans/keyloggers. You can lose everything you have and you won't be able to track down anybody.