If you know a simple way to get PG files to the Kindle Fire, just state it. If you know nothing, shut up.
It is simple to get PG files on a Kindle Fire, just use the web browser to navigate to a PG link that says "Kindle" and then click on that link. Then Complete action using "Browser" if presented with a choice of applets which know how to take action on mobi files. The Fire will say "downloading" and a second or two later you are done -- the book IS on the Fire -- the Fire is *much* faster than previous Kindles. The problem now is that Kindle Fire has followed Android behavior of downloading to "Downloads" instead of following traditional Kindle behavior of downloading to "Documents" -- which was historically more convenient. Read more below. It should be obvious to you by now Marcello, that I and others, especially at mobileread.com, have dealt with these issues in depth many months ago when the Kindle Fire first came out. The original Kindles, as I discovered years ago, allowed one to read mobi files which had been downloaded from the web directly, by going to the web browser, and clicking on them, at which time the Kindle would download them to the "Documents" directory. I further discovered that one could put a URL in a mobi book, and invoke this behavior also directly by clicking on that URL inside that book "catalog" , resulting in the "Magic Catalog." Other web browsers do not download directly to "Documents" but traditionally download to a directory called "Downloads." Unfortunately, the Kindle Fire has adopted this common web browser behavior rather than following prior Kindle behavior of downloading directly to "Documents." Presumably Kindle Fire made this change because it is an Android device, and Android applets expect downloads to happen to "Downloads." While Kindle Fire doesn't advertise the fact, it does come with an applet (Quickoffice) allowing one to manage and move files between folders, and it is also possible to pick up other good applets for free which also does these things. There are also applets that allow one to sync and send files to and from Kindle Fire (being a flavor of Android) directly to/from your PC via wifi, which can be helpful during book development. Also, Amazon has an applet for your [desktop] computer called "Send to Kindle" which allows one to send a file from your PC to the Amazon Cloud, with or without caching, your choice, and from there back down via wifi to your Kindle. I do book development on my PC, and then when I want to "take a break" and view how its going on my mobi device, I often find it easiest just to hit "Send to Kindle" -- even though it takes a couple minutes for the file to make it up through the Amazon Clould and then back down again. But its about as simple as clicking on the "Print" button. And I do book development in a downstairs office and often my Kindle is laying around upstairs somewhere, so the two are not collocated in the first place. The Kindles have always had a problem getting them to understand when you have added a new book file "behind their backs" and now they need to refresh their memory and add the new book to the list of books "they know about." The Kindle Fire has this problem somewhat worse than earlier models, presumably because the Fire is based on Android. One simple solution is to "three finger" power down the Kindle and then it checks and fixes its state of knowledge on power up. Most people find this reboot a pain, so there are other work-arounds. For example after a download one can use File Expert to navigate to a book file, put your finger on it for a second or two to bring up a context menu, hit "More" then hit "Open With" hit "More" again and then hit "Amazon Kindle" to read that book file in the "Amazon Kindle" applet. There may be better ways to do all this -- talk to an Android expert -- which I am not. For me overall, the Kindle Fire is more convenient than previous Kindles because it is "Android" -- even with all the limitations that implies -- and it is mobi8, which is miles less of a pain than mobi7 -- and it is much much faster and more reliable in everything it does, especially the web browser. Is it "better" than a Nexus 7 or a B&N Tablet? I think that probably depends on which family of devices you are most familiar with. It also probably depends on which of the various obnoxious monopolistic behaviors of the various obnoxious monopolistic major vendors one personally finds least onerous and odorous. I put up with the limitations of Amazon and mobi8 and even mobi7 for one simple reason: THAT is where the users are. It should also be obvious to everyone that part of these obnoxious monopolistic business practices includes selling reader devices into the market at subsidized prices, in order to try to "capture" your future business. When we buy these devices "below market" and then turn around and use them for free books, then the monopolists do not make their mark. And this makes them unhappy. And then they in turn "turn the screws" and try to engage in even more monopolistic behaviors in the future. Consider, for example, how Google has been constantly tightening the screws around "Google Books." Certainly everyone here must understand that we are not being their little "good buddies" when we don't buy product, but instead engage in making "free books" ! Certainly if you "buy into" an advertising motto like "Don't Do Evil" then you need to get your head examined. Don't inhale, and don't drink the kool-aid.