I use the Burt Bees stuff (with lemongrass in it I think?)
I did some research, and a couple of the active ingredients are supposed to be some of the most effective bug repellents that are used.
here's where I read it
http://www.bchealthguide.org/healthfiles/hfile96.stm
"These include repellents with p-menthane-3,8-diol (PMD), also known as lemon-eucalyptus oil. This product has been shown to be as effective as DEET, but protects against mosquitoes only for about 2 hours. Lemon-eucalyptus oil should not be used on children less than three years old. It should not be applied more than twice a day."
I got the feeling (from other sites) that the reason they said not to use it on kids under 3 because it hadn't been tested for that particular age group, not necessarily because it's not safe.
I should add that I don't think the burt's bees stuff has an age limit on the label.