Dark Horse Comics launched their digital comics store today.
https://digital.darkhorse.com/
Dark Horse is known for publishing a lot of scifi/fantasy comics, like Hellboy, Umbrella Academy, Star Wars, Conan, Buffy, Firefly/Serenity, etc.
Of particular interest is their series of Mass Effect comics. They've published two Mass Effect mini-series written by writers involved with the games, so if you're a fan of that series, you should check them out. They're pretty good, and actually tie into the games pretty well.
They have a lot of free issues available too.