What is happening is that I can start the integrated browser and point it to any address I want, incl. the onboard webserver. The pages need to be formated to fit to the screen, since there are no scrollbars and so on. I'll PM you an example of that, incl. your idea.
As long as these pages are html or generated via php, everything is ok.
I have tried to install several things, including my own php-shell (for issueing ad-hoc commands to the kobo). But everytime I submit POST or HEAD requests, the first click does nothing at all. When I click again, I get an "Ooops, something happened to the network connection" error. Sometimes the Kobo hangs itself after that.
I believe this is related to the webstore authenticating itself to kobo via a script called __utm.gif on the kobo server (which is requested during every UI interaction and includes many obscure paramters). The precice URL is http://webstore2.kobobooks.com/__utm...any=parameters
Since the Kobo thinkgs it's not authenticated, it somehow can't send POST's, as these would usually be purchases.