Marvel Comics, home of The Avengers and X-Men, has launched its Marvel Unlimited service as an iOS app. For $10 a month or $60 for a year, you can enjoy the "Spotify of Comics." Meaning, you have access to unlimited Marvel comics for the duration of the subscription, with the caveats that it's an HTML5 based reader, comics are at least six months old, and you can only store six at a time for offline reading.
Over 13,000 back issues are currently available. An Android version is in the works, as is an enhancement to store more than six comics. Marvel is also trying to fill holes in the back catalog, promising that the entire Iron Man collection will be finished around the time the movie comes out.