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.
Managerial accounting defines residual income in a corporate setting as the amount of leftover operating profit after all costs of capital used to generate the revenues have been paid. It is also considered the company's net operating income or the amount of profit that exceed its required rate of return. Residual income is normally used to assess the performance of a capital investment, team, department or business unit.
I wish I had more time to put into real estate. Given the run up since 2012, I may even be interested in selling my condo that I currently rent out. I need to get it appraised to really see what it’s worth, but I think conservatively it’s gone up ~50%, although rent is probably only up ~10% or so. I am bullish on rents going up in the future… mostly in line with inflation, or perhaps even slightly faster due to constricted credit and personal income growth which should provide a solid supply of renters. At this point, I just don’t want to manage the property. I’ll probably look into a property manager as my time is likely worth turning it into a nearly passive investment.
For example, you can design digital products, like animal clipart or a downloadable wedding poem that could be printed by the customer. Your design could be resold thousands of times without needing to create each item or ship it. Once you create your digital product and list it on a site like Etsy or Ebay, the revenue flows in with little oversight.

There are three main categories of income: active income, passive income and portfolio income. Passive income has been a relatively loosely used term in recent years. Colloquially, it’s been used to define money being earned regularly with little or no effort on the part of the person receiving it. Popular types of passive income include real estate, peer-to-peer (P2P) lending and dividend stocks. Proponents of earning passive income tend to be boosters of a work-from-home and be-your-own-boss professional lifestyle. The type of earnings people usually associate with this are gains on stocks, interest, retirement pay, lottery winnings, online work and capital gains. 
1) Save Like Nobody Owes You Anything. Passive income starts with savings. Without a healthy amount of savings, nothing works. Your overall “Money Strength” will be an F- if you do not build a financial nut. In our current low interest rate environment, you must save even more than before. It’s important to also realize that the savings I am referring to is AFTER-tax savings. You need to save money after contributing to your 401k and IRAs since you can’t touch pre-tax retirement accounts without a penalty until 59.5. Ideally everyone should max out their pre-tax retirement funds first, but if you don’t have enough funds and want to retire earlier then a decision to have more accessible post tax money will still work.

The U.S. Internal Revenue Service categorizes income into three broad types, active income, passive income, and portfolio income.[1] It defines passive income as only coming from two sources: rental activity or "trade or business activities in which you do not materially participate."[2][3] Other financial and government institutions also recognize it as an income obtained as a result of capital growth or in relation to negative gearing. Passive income is usually taxable.
Speaking from our own experience, you can’t be a passive McDonald’s franchisee. Every McDonald’s potential franchisee will need to complete at least thousands of hours of training before he/she would be approved to acquire a franchise and only if he/she has the financial resources to acquire a franchise. It could take years before one would get a single store franchise. Until the franchisee eventually has acquired multiple stores and established his/her own management team, the franchisee would have to put his/her nose to the grindstone and work his/her ass off every day. I won’t call it a passive investment by any stretch of imagination.
In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.