As it turns out, you can actually write apps for Kindles (the practice isn't supported by Amazon though).
Here's a simple news-reader thing i wrote over the past few days.

If Amazon doesn't support it how did you find out about it? Does Kindle have APIs which are documented? Then I'd say it is kind of allowed. How do you install apps on Kindle ?

@rayanon Well, they're not documented. The Kindle just runs webapps (using a thing called WAF - Web Application Framework) and Java programs called Kindlets. The webapp system only exists because the Kindle's interface is written with it. There are Kindle-specific APIs but I didn't need those, and the only documentation is unofficial and on some place called MobileRead.

To get webapps to run you first need to jailbreak your Kindle, and install a thing called KUAL, which is basically a nice menu to launch shellscripts from, and then run a script which adds your app to the Kindle's app database (if it's not there the program behind the. webapps will run but nothing will appear on screen). And finally, since the app database is just a way for the Kindle software to know how to launch each app (they don't actually appear anywhere if they're added to it), run a script to get your app launched via the app manager daemon.

@donoskaro Here you go!

@osmarks how did you find out about those?

@rayanon Which things specifically?