Here are a few products suggested by Lynne Chapman of BellaOnline. I also like Keune sun care line and I agree w/ her on the Biolage.
Also Charles Booth & Frederic Fekkai make a few summer products. And if you're in doubt... conditioner!
Protection From Sun and Chlorine
UV Protection
Aveda
Pue-Fume Brilliant Damage Control: contains a natural sun filter and antioxidant.
Biolage
Daily Leave-In Tonic: This is a light contditiioner containing sunscreen. It protects the hair and delivers body and fullness.
Bumble and Bumble
Sun Spray. It protects the hair from UV rays and contains Vitamins E and B.
KMS
Color Last Treatment. This rotects the hair from UV rays and the environment.
LC Legacy Styling System Every styling product contains sunscreen so that you can layer on protection.
Swim Barrier
Paul Labrecque Silk Creme
This protects the hair from the harsh effects of the sun and also safeguards color when used before swimming.
Leonor Greyl's Huile de Palme
This is a softening treatment that also provides waterproof protection.