That work-around is ingenious!
Short of buying a high-priced, site-tracking software program or service, I think your idea will produce some interesting stats. The only thing you may want to keep in mind is that you'll get more hits than just those from bookmarking clicks - especially depending on where and how you have your favicon set up. If yours is like mine, and is located in the templete's header.php file, it will appear on any and all pages of your site. So, if someone is surfing around your blog, you'll get hits for each page they view instead of one hit for the one visit. Worth exploring, though, as you could use the visitor's IP address to identify the duplicates appearing at or around the same time of that "session," and ignore them. However, on the flip side, if you focus on the stats from the urls of "referring" sites, you'll see how many locations are sending people to your site via links on theirs. Still, though, using your favicon concept with Amazon's tools is really clever! Frankly, what do you have to loose in trying? And it's free!
Just curious. Does your hosting provider have any site metering programs incorporated into its package? A few of mine do, and one offers several different "off-the-shelf" stats programs, like Webalizer, AwStats, and Analog Statistics, at no extra cost to track my site activity. They aren't all inclusive, but do provide useful info without your having to incur the expense of those cost-prohibitive site metering products.
I'd give it a shot and see what you think once you've had an opportunity to evaluate the results. In the meantime, I'll keep an eye out for any info I run across dealing specifically with tracking bookmarks, and if I run across anything, I'll let you know.
By the way, I submitted a Q to your reply on a post about displaying 1 or 2 of the most recent posts on a page, then titles only. The chain is here: http://wordpress.org/support/topic/177123
Sure would appreciate your input on that Q.