Read the entire post at forbes.com

Here are ways do-gooders can join in:

MicroPlace.com, launched by Ebay this past October, is a regulated broker-dealer that sells microfinance loans online as securities through the Calvert Social Investment Foundation and Oikocredit USA. Most such securities mature in three years and yield 3%. You need as little as $100 to get in. The Web site has attracted $500,000 so far. The prospectus can be found on the site.

So-called microfinance investment vehicles typically either resell a basket of debts held by microfinance institutions or make equity investments in lenders directly. Minimum investments range from $100,000 to $500,000. One of the largest, MicroVest ($39 million in loans outstanding), is typical in that it raises money via private placements and is therefore not registered with securities regulators in states where it is offered. To gauge a fund manager, you should request a prospectus; they’re usually not available on Web sites.

Downside: Expenses can be high, up to 2.5% of assets annually. Liquidity is as low as in a limited partnership or hedge fund: You have no right to withdraw before the announced close-down date (typically, in seven to ten years) and so would have to take your chances selling on the secondary market.

One other potential catch: If you invest in a microfinance fund incorporated offshore, you could get hit with a nasty “penalty tax” on “excess distributions” if the fund is liquidated and the right paperwork isn’t done. (That’s in addition to the normal tax on earnings from the investment, which might also drive up your tax accountant’s bill.)