You can add eBooks to the Kindle app on any Android device using the following instructions.
First the file has to be converted to the PalmDoc (*.prc) format.
Then it has to be copied over to the /sdcard/kindle folder on your Android device. You will then be able to open the eBook in the Kindle app.
This guide assumes that you already have a Dropbox account if you don't you can sign up for one here with a referral bonus of an extra 500MB
Here's how to do it without connecting it to a PC:
1. On the PC: Convert the book to *.prc format using Stanza (Open original file, then File->Export Book As->PalmDOC) and save in Dropbox folder.
The file should have a .prc extension.
2. On the Android: Open the Dropbox app and open the .prc file from step 1. It will be downloaded to the /sdcard/dropbox folder.
3. On the Android: Use ES File Explorer to move the file from /sdcard/dropbox to /sdcard/kindle.
4. On the Android: Open Kindle app and read the book.