Mostly this is for women, but I hope that some men will chime in and mention places where men can get summer sport attire that conforms to their own religious modesty laws.

Swimsuits:

http://www.aquamodesta.net/3-2604B-1 styles.html (conforms to Jewish standards; with addition of a Lycra/spandex hijab, would conform to Muslim standards)

http://www.ahiida.com/index.php?a=subcats&cat=20 (conforms to Jewish and Muslim standards)

http://www.wholesomewear.com/ (conforms to Mormon standards)

http://www.speedousa.com/index.cfm/fuseaction/products.browse/searchString/fastskin/page/1/showAll/1/?utm_source=adwords&utm_medium=plm&utm_campaign=SQ+-+LOW+Volume&utm_extra=dim2/Broad&utm_term=full+body+swimsuit (covers the skin admirably for sun protection, but a bit body-revealing for those whose concerns are primarily religious)

http://store.sunprotectiveclothing.com/canada/moreinfo.cfm?Product_ID=97 (again, more sun-protection than religion-supportive)

http://www.equatorsun.com/ (sun protection for children)

http://www.xen.co.za/swimwear/fullsuits/fullsuits.php?product=dive_suit (marketed as a dive suit, but equally suitable for sun protection)

http://www.mustaqim.co.uk/clothing/ (conforms to more liberal Muslim requirements)

http://www.primomoda.com/clothing-store/home.php?cat=1 (Muslim standards; the overdress is a bit short for Jewish standards)

Sportswear:

http://www.primomoda.com/clothing-store/home.php?cat=8 (Muslim and Jewish standards. I have two of these. They are really fashionable, but made of a fabric that doesn't allow much in the way of stretching and bending. Really only suitable for jogging, which is not my sport.)

Any others? Go ahead and post!