Passion PlayInvestors looking to expand their portfolios are putting their money where their hobbies are.

In five short years, the price tag on Larry Sirolli's loft apartment in Manhattan has skyrocketed 70 percent. But what's hanging inside his home represents his most impressive purchase: a late 1950s abstract expressionist painting by American artist Stephen Greene. Sirolli purchased the piece at an auction in Chicago for little more than $1,000 in 1999. Today, he estimates it's worth $60,000--a whopping 5,900 percent gain.

No amateur to the art world, Sirolli, 47, boasts 23 years at Sotheby's and one year as owner of New York City private art dealership and consulting business Sirolli Fine Art, which has brought in sales of $1.3 million so far. However, his investment play is becoming more commonplace. Individuals who once focused solely on stocks and bonds are diversifying into so-called "passion investments" like art, wine and even NASCAR.