For investors with an annual income or net worth of at least $100,000: 10% of annual income or net worth to a limit of $100,000 (again, net worth excludes the primary residence).

But Klein maintains that accredited investors are likely to be exempt from those limits-people who typically make $200,000 in each of the prior two years, or have a net worth of at least $1 million, excluding the residence.

Susan B. Quint, a Boise, Idaho financial planner, was initially skeptical of crowdfunding because of the risks. But now she believes it could help a couple of her clients fund their new lines of business down the road, when they otherwise would have had to seek out small business loans. As for her clients who want to invest through a crowdfunding portal, Quint says she may be hamstrung by Finra rules that prevent her from selling away from her current broker-dealer.

At least one Phoenix broker-dealer, Dinan & Co., has already launched a crowdfunding Web site, "ConfidentCrowd."  The site will require an entrepreneur posting a listing to be screened by a Finra-member broker-dealer. Founder Michael A. Dinan hopes brokers and financial advisors ultimately will use the site to raise capital for small business clients too small to raise capital through traditional means.

"Over the decades, we've had very small but promising early-stage entities approach our investment bank with a request that we help them raise capital," Dinan says. "But to raise $1 million in capital for a small company was not economically feasible for us."

The crowdfunding exemption, Dinan says, should solve that quandary. "My guess is that disclosure requirements and investor suitability standards for crowdfund offerings would be less than what a typical broker faces under a traditional Reg D private placement," he says.

For years, crowdfunding has been used by Web sites to launch social media campaigns and raise money for artists, filmmakers, charities, borrowers, college students and entrepreneurs. Among some of the more well-known crowdfunding portals are Kickstarter.com, Rockethub.com, Indiegogo.com and Peerbackers.com.

A May survey by Massolution, a Los Angeles-based crowdfunding research firm and advisor, cited 452 already-active crowdfunding platforms that raise money through equity participation, lending, donations or rewards (perks for donations). Crowdfunding portals raised $1.5 billion in 2011, and claim more than 1 million successful campaigns. Donation-based campaigns accounted for the highest number, the study says.

The Massolution study projects that crowdfunding portals will grow to 536 by year's end and that funding volume will double. Equity-based funding, though still illegal in the United States, is expected to fuel that growth along with reward funding.

Some fundraisers charge commissions that make hedge funds look inexpensive, however. Crowdfunding Web sites typically charge a commission on funds paid to fund-raisers, ranging from 2% to 25%, the Massolution survey says. Some charge a fixed fee per campaign. Some may only charge the fee if the campaign's goals are reached. Crowdfunding Web sites may also list fees for transactions and services, such as uploading videos for campaigns.