Of the 52 Killer Tricks for Your Kindle, some are useful only for the first 3 series (#'s 2, 3, 5, 6), others for Fire only (#8), others are so arcane and specialized as to be almost nonsensical (#'s 9, 15), some are DIY and may require more nerve than even I have (#'s 1, 14, 26, 42), some are only tangentially related to the Kindle (#'s 16, 30, 36) and on and on. So right away, you can simply skim this list and reduce it to something more manageable. Is it possible that your humble correspondent may have a few tricks that didn't make it to the list? Verily, I saith unto you: Yes.
As I'm using a Kindle Touch, some of the "killer tricks" (which I daresay would reveal themselves with a skim of the manual) don't apply. Some of the tricks reveal themselves with a simple read of the manual: keep the wi-fi turned off to save your battery, email PDFs to yourself, play MP3s, and so on. And I have, of course, already thoroughly documented my screensaver workflow.
There were a few things the original article missed, so allow me to add to the conversation.
For web pages
I would add Readability to #11 (Readability can include images and photos, Instapaper can't -- or didn't the last time I looked).
For public domain books in Kindle format (#3), I'd also recommend Project Gutenberg, which offer Kindle versions of its texts in .mobi format. You can download the Magic Catalog (.mobi file) and get a list of all the books and texts they offer. Click on a book title and it's downloaded to your Kindle in the background.
Even better: use your Kindle's browser to navigate to m.gutenberg.org, where you can have a more interactive experience searching for and downloading ebooks.
Another neat way to get Kindle-formatted public domain books is to navigate to this page on the MobileRead forums site and search the page for "MobileRead's Download Guide." Download that file and transfer it to your Kindle (or download it directly from the MobileRead page), wait a bit while the Kindle indexes it, and then you have a file containing a list and descriptions of 11,000+ books formatted by MobileRead members; click on a link to download the book in the background (wi-fi has to be on, of course). The file is updated daily. There's overlap between the MobileRead and Gutenberg lists, sure, but it's fun to compare them and see what they offer. I use both and sometimes just have fun browsing the lists.
I also like the Delphi Classics site, mainly for just knowing that it's possible to download the complete works of most any "classics" author.
Keep your Kindle software up to date
Bookmark the software update page and set yourself a reminder to check it monthly or whenever is convenient. You won't get any notice from Amazon that updates are waiting for you.
See what other Kindle owners are highlighting
One of Kindle's features is that you can highlight passages from any book or article you're reading and it's saved in a file called clippings.txt. Findings lets you upload your clippings.txt file so others can read what you've highlighted, and you can read what other Kindle owners found worth noting. It started as a Kindle-only hangout, but they've since rolled out bookmarklets and such so that you can highlight anything you see on the web and have it posted.
Convert clippings.txt to more readable formats
The clippings.txt file contains the contents of all the highlighted passages from everything I've read on the Kindle. So it includes tips and tricks, quotes I want to remember, procedures, beautifully written passages, etc.
You can open and browse the file from the Kindle home screen and it's easy enough to copy the file to my MacBook and open it up in a text editor, but it looks ugly and there is no easy way to browse the collection. So a lot of what I've highlighted is trapped in a file that is difficult to navigate, read, and use.
The amazing and free Clippings Converter site will transform the clippings.txt file into more attractively formatted Word, PDF, or (my favorite) Excel files. It provides a much better and easier method to process and re-use this text in other ways.
Yet, for all my snark...
The 52 tricks site convinced me to download Calibre (#16) and give it a try, and I'd not heard of the KIF project (#40) that lets you play old Infocom games on the Kindle, nor did I know of the justification hack (#44). Off now to do some minor-league hacking...