Kindle Fire

If you've got your hands on a Kindle Fire and are having loads of fun playing around with it but would love to have the SwiftKey keyboard to replace the stock Fire issue, you're in luck.  Any computer software or operating system is hackable, but because the Fire runs Android we already know how most everything works -- including the settings database.  Add a few Android hackers, who want SwiftKey on their Fire, and you have a solution.  The method itself isn't for the faint of heart, and you'll need to be rooted (you can un-root afterwards if you like) and have adb working.  I'll point everyone to the source link for the full instructions, but to help answer a few questions I'll try to explain what's going on. 

Amazon has removed the GUI from the settings menu that allows you to select an input method and set a default keyboard.  Android is still smart enough to know where to look for these settings, so we just have to find a way to set them, which can be done on your computer after pulling out the settings database, moving it to the USB storage, and editing it.  After adding the entry to the database for SwiftKey (or any other third party keyboard), you push it back in place, edit the permissions, and reboot.  It sounds pretty scary, and we won't blame you if you pass on this for now, but the instructions are very clear and will work if you follow them to the letter.  If you do give this one a run, be sure to shout out in the forums so others can benefit from your guinea pig-ness.  In the meantime, we're looking at alternative methods to edit the database while in place, and we'll update if and when we figure anything out.

Source: XDA-Developers