Matt McGarry tweets…
Untapped $20,000/mo newsletter business idea you can start this weekend
He goes into detail, but in brief 
The newsletter would target overseas marketers seeking US-based remote jobs.
3 sections in each edition…
Section 1: Good remote Marketing jobs readers can apply to.
Section 2: Marketing news and other relevant updates
Section 3: One hyper-tactical Marketing tip
Build a subscriber base from low-cost regions like India or South America at just $0.25 per subscriber = 20K new subs each month for $5K 
Monetization…
Make a free job board where USA-based companies can post Marketing jobs for overseas talent.
Once you have a solid base of jobs, you can charge companies $300-$500 for a “boost”—where you feature the job in the newsletter.
You could also provide a data-driven recruitment service…
charge between $2K to effectively become the head hunter