Nehemiah no longer directly offers down payment assistance.
The type of down payment assistance Nehemiah offered was called "seller funded" or "private funded" down payment assistance, where the money for your down payment actually came from the seller of the home. The seller would agree to pay Nehemiah X amount upon the sale of their home, that same X amount was the buyer's down payment which Nehemiah would provide at the closing table. The issue was that in a lot of situations this would result in an increased sales price, because if the seller is paying for the buyer's down payment they would want to increase the sales price in the contract by that same amount so the "net" is the same to them. So, back in October 2008 Congress passed a bill that prevented that type of down payment assistance.
Nehemiah Corp. didn't stop trying to help homebuyers with down payment assistance though, they actually have a nice searchable database of down payment assistance programs all over the U.S. which you can find at: http://www.ncf-wep.org/services-and-resources/down-payment-assistance-dpa-search.html
Those down payment assistance programs have income limits, often require someone to be a first time homebuyer, funds aren't always available, and other restrictions, but that's the norm for down payment assistance - it's only for those who the assistance providers have deemed could "need" it and not everyone.