My Google fast-flip brought up this article on the U.S. News site: 21 Ways to Make Extra Money In Retirement. It was aimed at present retirees. The advice ranged from one-time money raisers (sell your stuff) to on-going money savers (ask for discounts, use a rewards credit card) to on-going money makers (consult, temp, garden, blog, etc.)
Starting up a blog, for example, is not fast money. (Take it from someone who knows.) It can take a year to make even $100/month at a blog, unless you're a superstar like John Chow or the like. It can take a few months just to break even on great, yet inexpensive hosting. It's work, even if all of the inroads have been paved.
Everyone can only start where they are, but wouldn't it be far better to start planning for extra retirement income streams now rather than wait until the gold watch is in hand? Even getting a head start of a few years — say, at age 55 for someone planning to retire from their day job at age 65 — can mean all the difference in the world. Ten hours per week, fifty weeks per year, for ten years is 5,000 hours, and that's more than enough time to become more than proficient at just about anything. Then, when age 65 rolls around, there's a blog with several thousand readers, one or two thousand posts, and a nice supplementary income stream.
Extra income streams of this kind compound much the same way a savings account does. The time put in at the beginning writing posts doesn't bring in much. But the more posts that go up, the more the search engines have to feast on, the better the writing is (or should be), and the higher the rewards for doing the same amount of work. That rewards comes with time and consistent effort. Postponing the effort means concentrating the effort (working much harder) to achieve the same results.
So if you're a bit away from retirement, there's no time like the present for starting up those extra income streams! Your retirement bank account will thank you.