I believe there's an extension (for Firefox, at least) that allows you to create custom buttons for bookmarklets. In the near future, a native solution will be

I believe there's an extension (for Firefox, at least) that allows you to create custom buttons for bookmarklets. In the near future, a native solution will be available -- i.e. I'm working on a thin extension, for all browsers, that will act as Readable's launcher (with benefits like keyboard shortcuts, an icon, and slightly faster load times).