Look for larger city NGOs, especially ones that are starting with new grants. The small guys probably don't have any development staff. Another route is check out the NGOs you like and see what member organizations they belong to (i.e. the child care resource & referral agencies in California usually belong to the California Child Care Resource & Referral Network, CCCRRN, and the National Association Child Care Resource & Referral Agencies, NACCRRA) through such member agencies you might find agencies that do their own development.
Don't expect cutting edge technology or being able to do free wheeling development, there is a lot of bureaucracy in NGOs, though sometimes yo get lucky. But if you do get some latitude in making development decisions make sure you pick technology that's well established (Microsoft Tools are still quite popular, though some use LAMP stack).
