Answer
HUD has long recognized the important role that down payment assistance programs (DAP) play in providing affordable housing opportunities. There are three categories of DAP assistance providers:

1) Nonprofit and Nonprofit Instrumentality of Government DAPs
Nonprofits and Nonprofit Instrumentalities of Government that provide assistance in the form of a second lien in conjunction with an FHA first mortgage must be approved by HUD. HUD maintains a Roster of the Nonprofits and Nonprofit Instrumentalities of Government that have been approved. This DAP approval roster is maintained at http://www.hud.gov/offices/hsg/sfh/np/sfhdap01.cfm

2) Government Entity DAPs
No HUD approval is required for Government Entities that provide secondary financing in the form of a second lien in conjunction with an FHA first mortgage. HUD does not maintain a list of Government Entity DAP providers. Lenders are responsible for assuring that a Government Entity DAP meets all appropriate FHA requirements.

3) Gift Programs
HUD does not 'approve' down payment assistance programs in the form of gifts administered by Nonprofits and other charitable organizations. Lenders are responsible for assuring that the gift to the homebuyer meets the appropriate FHA requirements and that the transfer of gift funds is properly documented.