I spoke with a lender today who has 100% financing available for buyers with credit scores of 580 and above. The program also allows a seller to pay up to 6% towards a buyer's closing costs - a great deal for first time buyers. It is through the USDA and the property must be in an approved area. It doesn't work for Dallas County, but there are areas in Tarrant County that qualify. Both existing homes and new homes work as long as they are in the approved-target areas. There are some great communities that fall into these zones.
Email me for more details. If your credit score is close to but below 580, this lender has a team that can help raise it in as little as a month depending on your situation.
Keal