Stock dividends: Some stocks, especially stocks from big corporate standouts, pay dividends to shareholders based on the number of shares they own, and the percentage of the stock price on the dividend date. For example, if a company pays out 3% on a stock that's trading at $100 per share, you'll earn $3 for every share of that stock you own. Add it up and that can be good take-home pay as a passive investment.
Amazing that you saved between 50% to 75% living in NYC…I think that is one thing holding me back…the cost of living here. I’d like to invest in real estate, but I can barely afford to buy a place to live. I don’t need a large income to be happy, but I probably do need an income to support living in NYC as we don’t plan on leaving. The only thing I’m doing at the moment is saving in my 401K, IRA and a I dabble in stocks and P2P lending.
This venture requires both time and money, but it is certainly worth it. Making low-risk investments with your savings offers higher dividends than letting the money in the bank. While buying stocks in large corporations comes with a high degree of risk, mutual funds are relatively safer and less volatile. They also offer higher return-on-investment compared to fixed or recurring deposits made in banks.
Audiobooks are witnessing a surge in popularity when compared to their text-based counterparts. If you have decided to write and publish an eBook, converting it into an audiobook requires little effort and is a great way to bolster your income. Amazon's Audible ACX platform connects authors with producers who can turn their written work into professional grade audio. Once that's done, the audiobooks are put up for sale on Audible and iTunes.
Investing in coins and collectibles: Buffalo nickels and Spiderman comic books are good examples of coins and collectibles that can rise in value, and thus offer opportunity for passive income investors. You'll need to get up to speed on the value of any coin or collectible under consideration, but once you do so, you're on the way to price appreciation on a commodity you'll be paying a lower price to buy, and will garner a higher price when you sell.
An obvious example is over exposure to bank stocks, which have been excellent investments for over a century.  Though a foundation of most portfolios, bank stocks do involve more risk at certain stages of the economic cycle than many realise.  Being less exposed to bank shares in the last few months could have preserved some capital.  So, a more diversified approach can help mitigate some of these risks.