One of the more popular pop ups for mac users is Mackeeper which promises all sorts of benefits.
In my opinion and many other mac users I would not install it as on the mac computers that I have seen with it on , it slows the computer down dramatically and does not really do that much and there is a vast improvement when you uninstall it.
Once again it is a mystery program offering all sorts of benefits but does not appear to deliver.
Don’t believe me , check out this story on Mackeeper from Macworld : MacKeeper celebrates a difficult birthday under the cloud of a class action lawsuit