Without mentioning any names, I'm currently signed up with 2 "cloud" mining sites with minor investments of about 10$ each.  I've managed to make back about half my investment (if you want to call it that) after about a week.  These sites have since been flagged as scams and I think the only reason I may be seeing a return is due to the size of the contributions I've made.  I'd be scared to invest more than that.