ComiXology has quickly established itself is the application to read comics on iPhones.  While some digital distribution channels like the PSP are just launching, ComiXology is already adding new features it’s users can enjoy.  Beginning today, the Comics app launches some new options by offering digital trade paperbacks, as well as new software updates that include story-arc tracking and an option for right-to-left reading.

The company already has more than 700 comics currently available from publishers as diverse as Marvel and Image to Th3rd World Studios and Zenescope. Many of the comics are free or only 99 cents and can be downloaded from right inside the Comics store, without having to visit another website or leave the application. As a result, Comics is the only iPhone comics store to remain in the Top 10 Free Book apps.

ComiXology is also branching out with exclusives including The First Daughter, a new comic from Keenspot, a publisher that formerly used their own iPhone apps but is now switching to the Comics app. The other original comic beginning today for iPhone is X: The Unknown from Id Ego and Tim Smith.

“Story-arc” tracking will allow users to lump together stories that tie together.  For example Marvel’s Civil War or Dark Reign story arcs ran across numerous series.

ComiXology is also pursuing digital distribution outside of the iPhone.  Here’s hoping for one service that allows me to read my purchase across multiple platforms.