Credit Card Sign-Up Bonuses – This one might not seem like a source of income but ever since I discovered how lucrative churning credit cards can be I consider it part of my income. Just last year alone, I made over $10,000 tax free in travel, cash and gift cards from various sign-ups. It’s not as simple as just signing up for a card though, it requires a lot of research and some maintenance every couple weeks.
This is mostly passive once you have it all set up, but it does take a lot of work at the beginning. Real estate investing also requires occasional maintenance. Currently, we invest in a couple of rental properties and earn about $500 profit from each per month. You can read more about my rental properties at How and Why I Became a Landlord.

Don't mistake passive income with zero work. It's still work, it's just that your income is not directly tied to the hours worked. Anyone who owns rental properties knows that it's considered passive income but there is quite a bit of work involved. The work is front heavy but if you are lucky, you can collect rental checks without incident for many months before having to do work.
My favorite type of semi-passive income was rental property because it was a tangible asset that provided reliable income. As I grew older, my interest in rental property waned because I no longer had the patience and time to deal with maintenance issues and tenants. Online real estate became more attractive, along with tax-free municipal-bond income once rates started to rise.
In May 2014, the World Bank reviewed and proposed revisions to its poverty calculation methodology of 2005 and purchasing-power-parity basis for measuring poverty. According to the revised methodology, the world had 872.3 million people below the new poverty line, of which 179.6 million lived in India. With 17.5% of total world's population, India had a 20.6% share of world's poorest in 2013.[339] According to a 2005–2006 survey,[340] India had about 61 million children under the age of 5 who were chronically malnourished. A 2011 UNICEF report stated that between 1990 and 2010, India achieved a 45 percent reduction in under age 5 mortality rates, and now ranks 46th of 188 countries on this metric.[341]

Retirees are paying a high price as the world stimulates its way out of the GFC (Great Recession).  After a 30-year bull market to the lowest interest rates the world has ever seen, bonds have become highly priced and now don’t generate enough to meet income needs.  Just 5 years ago the average income from $100,000 invested in a 10 year Australian Government Bond (10yrs) was $5,600 p.a.  – now it’s less than half at $2,600 p.a.