My advice is to do a SaaS product of some form. You can do it in a low key sort of way that doesn't take much of your time (or make you quit your job or neglect your family), and it will generally make you more money each month (unless you're doing something strange that churns all your existing customers away each month).

Avoid anything ad-funded, such as blogs and whatnot. The ability to write software is way more lucrative than the ability to write words. Leverage that if you can.