Low-cost or free health insurance is available in almost every state for America's children through the State Children's Health Insurance Program (SCHIP). Passed by Congress in 1997 in response to the growing and shocking numbers of children without health coverage, the program is federally funded but implemented by each state. You can also learn about how to qualify for the SCHIP program and find information about its availability in your state at the Insure Kids Now website.
Another good source is the National Health Law Program's children health page. Both sites provide links to other child health advocacy groups.
If you'd like to get involved in an outreach effort to help eligible children get signed up for health insurance, you can get tools from the Center on Budget and Policy Priorities' Start Healthy, Stay Healthy Campaign.