Eyebrow growth: Marini and FNS Nutrilash work
Marini seems to be slightly more effective, but you need to be aware that it contains prostaglandin, a glaucoma drug. I certainly won't use it on eyelashes (since possible side effects include the color of eyes changing and red, burning irritation) until its safety has been demonstrated.
FNS Nutrilash, made by Osmotics, is a safe blend of amino acids and vitamin Bs. It is for eyelashes and eyebrows. I have been trying it out on both and can say that the effect on my lashes has been non-existent. My slightly moth-eaten looking brow has filled out nicely, however. I find the applicators a bit fiddly (pictured above).