Cnet’s Crave gadget blog has an article about these free comics:
One of the under-the-radar killer apps of Apple’s iPad is the collection of comic book storefronts (which also double as comic readers). They’re all free, and connect you to virtual comic shops that sell digital issues of comics for about $2 each–with transactions handily conducted through Apple’s app store back end.
There are official Marvel and DC Comics apps, along with indie apps such as Comics + app from iVerse, IDW Comics, and the Comics app from ComiXology, which sell titles from a variety of large and small publishers. All of these apps have a very similar layout, and many sell overlapping products. Even better, they all have a frequently changing collection of free comics available to download, making it easy to build a small virtual comic book library for the low, low, price of free.
