Although you are loathe to find a helmet *without* a Snell approval sticker on it anymore, I wonder if Snell is all it is cracked up to be.
Check out this article.
http://www.motorcyclistonline.com/gearbox/motorcycle_helmet_review
Some things I found interesting:
To get a Snell sticker the helmet looking to be certified has to be able to withstand a 300G impact. ( I won't get into the particulars, you can read the article.)
Now injuries in trauma centers (at least the one I worked in) are generally measured using an AIS scale of 1-6. You give each part of the body, (head, limbs, etc.) an AIS rating. a rating of "1" means you are barely injured whereas a "6" means you will not survive if this AIS is head related.
With respect to head injuries:
A hit of 200-250 G's will give you an AIS of "4". A hit of 250-300 G's will give you and AIS of "5". 301 G's will give you a "6".
So the Snell sticker only means that the helmet has been tested and found to withstand a shock that is just 1 G short of killing you.
I guess that is better than nothing, right? (Not being sarcastic)
As a side note: Since the inception of the Snell testing this standard has not changed.
Take this for what it is worth of course, this *IS* the internet. Definitely a good read though.