Long before Android became common on tablets, much less started showing up on ereaders, Pocketbook had quietly made a name for itself by supporting a framework of 3rd-party apps on its ereaders.
That framework was never very well organized, and it was never very well developed on a technical level, but it is possible to find and install apps on the InkPad and other Pocketbook ereaders.
I have not been able to install any additional apps on my InkPad, but it did ship with thirteen (13) apps. This excludes core InkPad functions like the settings menu, bookstore, and stock reading apps, but includes things like the Dropbox client.
Table of Contents
For example, I would have really liked to have been able to read digital comics on the InkPad. I would have also liked an Epub app with better control of the formatting.
One thing I have noticed in using the T68 Lynx and the T61/Illumina (2 ereaders which raun Android) is that the apps I used most on those devices focused on reading of one kind or another. Apps like Pocket were becoming more valuable to me as time went by.
Given Pocketbook's head start in running apps on ereaders, this is something they should have figured out first and built on as a way to add more value for their customers.
If you would like to develop apps, check out the SDKs on SourceForge. They were last updated in 2011, which should give you an idea of how well 3rd-party apps are supported by Pocketbook.
If you would like to install additional apps, well, that's going to be a little harder to do. There's more to it than simply copying a file and clicking the install button.
At a minimum, installing an app will involve going into the system folder and editing a config. You'll also need to identify the version of the app compatible with your specific Pocketbook device and copy the app file to the applications folder (and sometimes also to the system/bin folder). For more details, ask over at MobileRead.
I have not been able to install any additional apps. This is due in part to the fact that the process is a PitA, but also because I made the mistake of updating my InkPad from a v4.x firmware to a v5.x firmware. Most of the apps were developed for the older frmware.