You Don't Have to Quit Your Day Job For many, the pros outweigh the cons when it comes to starting a business while still employed.

When injuries from a motorcycle crash made it difficult for Nanda Holz to ride a bicycle, the Petaluma, California, engineer found that pedaling a recumbent-style bike let him get back on the road. When he moved on to crank-forward bicycles and his local bicycle dealer showed no interest in selling the distinctive bikes, Holz, 34, became a part-time entrepreneur. "I saw an opportunity," he says, "and started dabbling."

Today, Holz still works full time as an engineer, but he's also the founder and owner of Spin Cyclz, selling bicycles to Northern California locals and to customers worldwide via his website, spincyclz.com. Selling bikes gives him something to do in his off hours besides ride, he says. It's also starting to turn a profit: Holz brought in 2008 sales of about $100,000, with a $16,000 profit. "I'm starting to turn the corner," Holz says of his part-time venture.