My sites were hit by the updates on July 18th and August 21th (not exact dates, as I can't really remember precisely when the updates took place). However, they have bounced back and traffic is now better than ever.

I won't go into too much detail, but I did the following.

1. The first thing I did was work to remove duplicate content. Now, people will say that Google is advanced enough to know that excerpts found on category and archive pages and so on are not counted as duplicate content. This may very well be true, but I simply did this to fix one more thing that may have affected my rankings.
This is in fact a short term measure, as later on down the line I will turn category pages into very user friendly, useful, unique pages. For now, though, I don't want them indexed.

2. Use a text browser to see what Google sees. This goes a long way in helping you to optimize your site.

3. Use just a few affiliate links per page. I had pages that had a number of (10+) affiliate links on them. I worked to decrease this number down to 3. CTR is actually at 30% now, which is better than it has ever been, even though there are less avenues for users to visit Amazon. Conversions are also better than ever. Strong CTA's are all that are needed.

4. Perhaps most importantly, add pages with no affiliate links on them. For the next month, I'm doing nothing but writing this kind of content. This tells Google that you're not just here to make money, keeping me safe from further updates. Long term, anyone?

5. Turn your site into something that users really benefit from. Amazon marketers get a very bad rap on this forum, and for good reason to. When I'm checking out the competition all I see is crap - sites that scream I'm simply here to make money. I'm here to make money too, but I want to do it in a way whereby both readers and myself benefit. Turn it into a win-win situation. I spent a good few weeks completely redesigning my sites (I never felt my content was the issue, though), to improve user experience.

How do you know when your site is useful? I use 3 metrics - bounce rate, average duration and conversion rate. I'm inclined to believe that conversion rate is the most important. This is because if my content is rubbish readers won't be pulling their credit cards out to purchase $500+ products within a 24 hour time frame (Amazon cookie length).

6. Don't accept failure. In other words, work your ass off until you find something that works. This means test, test, test.
I'm not the kind of guy who would ever fit in working a 9-5. In fact, I've never had a real job and I fully intend to keep it that way. Waking up early, always having to work everyday, income being capped until I get promoted etc. Ugh, I literally can not think of anything worse - perhaps because everyone in my family is or was self-employed for most of their life. That's why we got into IM, right? Well, remember this when times are hard.
Don't be sold on WSOs' hype - I doubt anyone is stupid enough to tell others how they earn $10,000 a month for just a few thousand dollars in return. I bought 2 WSOs in my life and both were pretty much useless.

Everything I've listed above is common sense - no secrets here, because they don't exist - which is why I have no problem telling others.