| Home & Kitchen | 50% | 60% | 70% | 80% | 90% | off |
| Electronics | 50% | 60% | 70% | 80% | 90% | off |
| Appliances | 50% | 60% | 70% | 80% | 90% | off |
| Beauty | 50% | 60% | 70% | 80% | 90% | off |
| Grocery & Gourmet Food | 50% | 60% | 70% | 80% | 90% | off |
| Video Games | 50% | 60% | 70% | 80% | 90% | off |
| Computers | 50% | 60% | 70% | 80% | 90% | off |
| Clothing, Shoes & Jewelry | 50% | 60% | 70% | 80% | 90% | off |
| Women | 50% | 60% | 70% | 80% | 90% | off |
| Men | 50% | 60% | 70% | 80% | 90% | off |
| Girls | 50% | 60% | 70% | 80% | 90% | off |
| Boys | 50% | 60% | 70% | 80% | 90% | off |
| Baby | 50% | 60% | 70% | 80% | 90% | off |
| Amazon Instant Video | 50% | 60% | 70% | 80% | 90% | off |
| Apps & Games | 50% | 60% | 70% | 80% | 90% | off |
| Arts, Crafts & Sewing | 50% | 60% | 70% | 80% | 90% | off |
| Automotive | 50% | 60% | 70% | 80% | 90% | off |
| Baby | 50% | 60% | 70% | 80% | 90% | off |
| Sports & Outdoors | 50% | 60% | 70% | 80% | 90% | off |
| Books | 50% | 60% | 70% | 80% | 90% | off |
| CDs & Vinyl | 50% | 60% | 70% | 80% | 90% | off |
| Cell Phones & Accessories | 50% | 60% | 70% | 80% | 90% | off |
| Collectibles & Fine Art | 50% | 60% | 70% | 80% | 90% | off |
| Credit and Payment Cards | 50% | 60% | 70% | 80% | 90% | off |
| Digital Music | 50% | 60% | 70% | 80% | 90% | off |
| Gift Cards | 50% | 60% | 70% | 80% | 90% | off |
| Health & Personal Care | 50% | 60% | 70% | 80% | 90% | off |
| Industrial & Scientific | 50% | 60% | 70% | 80% | 90% | off |
| Kindle Store | 50% | 60% | 70% | 80% | 90% | off |
| Luggage & Travel Gear | 50% | 60% | 70% | 80% | 90% | off |
| Magazine Subscriptions | 50% | 60% | 70% | 80% | 90% | off |
| Movies & TV | 50% | 60% | 70% | 80% | 90% | off |
| Musical Instruments | 50% | 60% | 70% | 80% | 90% | off |
| Office Products | 50% | 60% | 70% | 80% | 90% | off |
| Patio, Lawn & Garden | 50% | 60% | 70% | 80% | 90% | off |
| Pet Supplies | 50% | 60% | 70% | 80% | 90% | off |
| Prime Pantry | 50% | 60% | 70% | 80% | 90% | off |
| Software | 50% | 60% | 70% | 80% | 90% | off |
| Tools & Home Improvement | 50% | 60% | 70% | 80% | 90% | off |
| Toys & Games | 50% | 60% | 70% | 80% | 90% | off |
| Wine | 50% | 60% | 70% | 80% | 90% | off |
While this may be an obvious step, I wanted to take the opportunity to explain a bit about the deal finder. First off, you must select a category OR enter in some search terms -- it's just the way it has to be, because that's how Amazon's hidden "percent-off" feature works. Yes, that means you can't easily search all of Amazon for great deals, but at least your results won't be overly cluttered with products in which you have little to no interest.
Secondly, it's important to understand exactly what's getting returned by the deal search. You see, Amazon has, within its wealth of product data, historical price data. In other words, Amazon knows how much each product has ever been -- and it knows the specific price that each 3rd party retailer has ever priced the product at. With that information, Amazon allows you to search its website (through a somewhat secret path that the above deal finder utilizes) by how much every product has been discounted.
Continuing on the point above, although Amazon has all of the data needed to provide valuable search results, sometimes the products returned by a "percent-off deal search" are a little strange. And here's why (or at least what I think): Amazon takes the top price that any retailer (Amazon themselves or a 3rd party vendor) has ever posted for any given product, and uses that as its "starting point," and then compares that price to the current price to decide on how much that product is discounted. Now, this is where the product comes in; someimes retailers accidentally post items for really high prices -- like a brand new Hanes t-shirt for $4000. Even after the retailer corrects the price, Amazon still remembers that the shirt was once $4000, and uses that in its comparison. So, if that shirt is now $10, that's a 99% off deal.
Another problem is that is gets more convoluted from there, because we really don't know how the "secret" percent off actually works on Amazon's side. We can't control which prices it uses for reference, and we have very little control over whether or not it looks only at the prices Amazon itself has set for a given product, and the prices set by third party retailers.
The Amazon deal finding search engine above still finds some pretty amazing deals, you just have to sort through a small amount of clutter. Just remember that a discount isn't always a deal. And this brings me to my next step.
As I explained above, just because you're finding a heavily discounted product in the Amazon percent-off product search results doesn't mean that the product is actually a great deal. Thankfully, there are all kinds of price-comparison engines all over the web that you can use to compare the price that Amazon is showing you against the prices of retailers all over the web. My personal favorite?
Check out Google Shopping, a feature of Google's search engine functionality that allows you to perform price comparisons on the same product across hundred (if not thousands) of online retailers. It's got all kinds of awesome features, like the ability to include shipping price (to a specific zip code, even), and filter your results a ton of different ways, which is really helpful when trying to compare prices on obscure products (like specifically-colored knitting needles, or something along that line).
One of the main things that makes Amazon great is the free shipping! Personally, I've paid for a subscription to Amazon Prime, and I'll never look back. With Amazon Prime, you get free shipping on everything that Amazon sells (except for some small "add-on" items, and you can even get free "prime" shipping through some third party retailers.
But I know that Amazon Prime isn't for everyone. If you're not ready to get Prime, then no worries, 'cause you can still get free shipping, as long as you hit a $30 threshold, which is where this deal finding search engine really shines.
Use the Percent Off Amazon Deal Finder to find really cheap items to help get you past that thirty dollar mark. For example, if you've got $28 worth of items in your cart, add some $2.50 batteries, or something along those lines, to bump you up past that threshold, and BOOM, you've got free shipping!
Finding the best deals that Amazon has to offer
Note: the above article is a quick primer on how the Percent Off Amazon Deal Finder works
Using Amazon coupon codes: important things to remember
Note: this one's an overview on Amazon coupon codes, and how to avoid the fakes
Is it possible that Amazon hides the best deals?
Note: this guy is about debunking the myth that Amazon "hides" some of their best deals
PercentsOff