Dark Horse Comics released their iPad app today. You can download the app for free here Dark Horse Comics for iPhone, iPod touch, and iPad on the iTunes App Store and here's the corresponding website. https://digital.darkhorse.com/
There are a lot of free comics on the site to download immediately (Fray, Falling Skies, Abe Sapien, Hellboy, as well as many others.) All you need is an e-mail address to register. Enjoy!
P.S. I have no affiliation with Dark Horse.