Snell Memorial Foundation is a private organization that tests various riding helmets, from bicicle to motorcycle to automobile. It is a standard that works in parallel with the mandatory US Department of Transportation standards.
Unlike Consumer Reports, which takes a hard line stance on funding from any company whose products it tests, Snell recieves 90% its funding from the manufacturers of the helmets it tests, and the rest from donations. Snell addresses this in its response to a New York Times article criticizing them on this and other things.
Though Snell receives no government funding, it does get funding by selling approval stickers, which likely utilizes government protection of intellectual property to prevent forgery.
There has been some controversy about the quality of Snell's helmet testing standards, largely from noted motorcycle safety researcher Harry Hurt. Snell has responded to him as well as to a critical New York Times article. In particular, Hurt's opinion is that the US Department of Transportation's standards are time tested and sufficiently useful. He believes that, though Snell has a drop test for higher speeds, they do not reflect realistic crash situations.
However, as evidence that Snell's standards are none the less respected, Snell product approval is still cited in Motorycycle Magazine's 2010 buyer's guide. There are also many certified helmets listed on Snell's website, indicating that many helmet manufacturers see fit to pay for the certification.