Carotenoids, like the ones cherrysilver listed, will add some of their own pigmentation and can help protect against sun damage.
Those two alone should add a slight cosmetic darkening of your skin without any sun. With sun, in my experience, tyrosine is effective in increasing tanning.
Vitamin D. Someone correct me if I'm reading this wrong: http://pmid.us/6175546
Any antioxidant should be photoprotective. If you pick an antioxidant and search pubmed for it and photoprotection, you will probably get hits.
There's something called Fernblock.
It's not a supplement, but Skinbiology sells copper peptide suntan lotion. Any of their copper products should be photoprotective, but I suspect their GHK lotion is better even though they downplay it. I use their products and had enough sun exposure that I would definitely have had a painful sunburn, but had no pain whatsoever. Redness maybe, but no pain. It's cool. It's also good post-sunburn. It can sting pretty bad putting it on a burn, but after a couple minutes feels better.
Other topical antioxidant lotions, like aloe vera, can have similar protection. Again, pick any antioxidant and it's probably photoprotective topically.
Edited by ta5, 18 March 2012 - 01:39 AM.