Unless you go with a Bike Helmet, you'll probably find all skateboard helmets offer about the same level of airflow. This is due to the the padding, and generally less aerodynamic design (since high speeds aren't expected). Having said that, there are some pretty cool helmets that offer good ventilation:
*Bern Unlimited Morrison Helmet
All three above are bike helmets, but look similar to skate helmets with the visor off, and are highly rated on Amazon.