We've added direct Kindle Fire support. So instead of a PDF with no table of contents with the native reader you can now get a fully indexed MOBI optimized for the Fire.
You'll see there are 2 Kindle Fire options, one normal and one that says 150%. Both can be zoomed by double-tapping and doing the normal 2 finger zoom, and clicking the X in the upper right to close. The 150% just includes extra data so that zoomed views look better. If you don't need that then we recommend the normal view as it will be a smaller file to download.
Right now, you can upload these files to your Fire using USB, Send to my Kindle or emailing the file to your kindle.com address. Direct download works but will need a file manager to move them to the correct location.
Soon we'll offer the option to send directly to your kindle.com address from the website so you'll have the data in just a few minutes(and won't need to wait for our system to convert, it will automatically email when it's done.)