Before last year, Ed Medley had never invested in commercial real estate. Now, he's a part-owner of shopping malls, mobile-home parks and apartment buildings from Los Angeles to Tennessee.

Dr. Medley's springboard into real-estate investing was supplied by a process known as crowdfunding—the sale of shares in a venture, in this case real-estate projects, to hundreds or even thousands of individual investors. Dr. Medley, a consulting engineer and geologist in San Mateo, Calif., has invested in 15 properties, with a minimum of $5,000 in each.

"Being able to invest relatively small amounts of money into different real-estate ventures was appealing" as a way of limiting risk, he says.

Clearly, other real-estate investors feel the same way, with new websites springing up that allow individuals to buy stakes in everything from self-storage facilities to luxury hotels.

"The interest is huge," says Scott Whaley, president of the National Real Estate Investors Association in Cincinnati. "There's massive demand, both from entrepreneurs who want to get access to capital, and from people who want to invest capital."