if you only need a few miles (to refresh expiration date) then there are a few ways, including completing surveys.
But if you are looking for big miles then you pretty much have to stick with chase sign up bonuses.

There was a 25k miles for directv signup , 1-2k for dining programs, shopping portals for a few miles, etc. Oh and there was/is a wine program to earn like 2-3k miles .