Droid Comic Viewer, is on the market, it will read cbr cbz zip and rar, as well as acv jpeg png bmp and image folders.. I use it to read stuff I downloaded ages ago, if your into Mange check out Manga Droid or OneManga, all of these are on the market for my hero so I don't know if they will work with a droid
Manga Droid works on the droid, but it's a terrible app... it actually shows ads while reading, taking up valuable screen space. If they come out with a paid, ad free version, it will be worth checking out, though.