URL Rewrite: Adding keywords - asp.net

Question

I was looking at amazon.com and noticed for a product like: "Really Really Really Long Book Title," they will have a URL like: "amazon.com/Really-Long-Book-Title/ref?id=1&anotherId=2,"
and for a short title like: "Success," they will add other words, like the author name: "amazon.com/Success-John-Smith/ref?id=1&anotherId=2." If I remove these words, like so: "amazon.com/ref?id=1&anotherId=2," the URL still resolves.
Does it hurt SEO to have multiple URLs that resolve to the same page?
How are these words even added to the URL? Is it done programmatically, or do they have someone hand-pick words and store them in a database for each product?
I've been trying to expand my knowledge about SEO so I'd really like to learn how this is being done as thoroughly as possible. I'd greatly appreciate the recommendation of any resources, and also advice based on person experience so that if I implement URLs like this, I can do it correctly. I know I can Google this stuff, but there always seems to be 1,000 ways to do something and I'd just to hear some personal recommendations.
For what it's worth, I use asp.net 4.0 (c#) and the IIS7 URL rewrite toolkit.
Thanks a lot!

Answer 1

IIS7 URL rewrite toolkit is a best tool to use in your case. Here are my answers to your questions.
Does it hurt SEO to have multiple URLs that resolve to the same page?
It does not, as long as you show search engines which URL is a primary one. You can do this by adding rel="canonical"in the primary link page. The best example of this is StackOverflow, which is doing very well in terms of SEO. Now, if you use http://stackoverflow.com/questions/5392137/ you will be pointed to this page, if you use http://stackoverflow.com/questions/5392137/url-rewrite-adding-keywords you will be on this page as well. Obviously the second ULR has more keywords, which is great for SEO, and it is more user friendly as well, since users know what the URL is all about.
How are these words even added to the
URL? Is it done programmatically, or
do they have someone hand-pick words
and store them in a database for each
product?
If you are a developer, then it is not your responsibility any more. SEO is 20% technical, 80% marketing(it is my rough calculation, you know the point.:-)). Those marketing folks should handle that after you give them an access to write or rewrite ULRs. They may find some keywords and add some of them in URL based on their tactics. Elad Lachmi gave a good answer on this question. StackOverflow is using question titles as a URL,which is reasonable. Hiring lots of SEOers to find keywords based on different questions and then manually add to URLs is not a good option for SO. But for commercial web sites, it is worthwhile to hire someone to manually do it. The answer is based on what kind of web site yours is.
Hope this helps

Answer 2

I love the rewrite toolkit because you can do ANYTHING!
From my experience, letting the content editor set whatever URL they like is the best option. Computer are not big on semantics. You can create set rules, and they might be ok (It`s not that hard to tell a computer "if the title is not long enough, add the author name"), but since a human adds the products anyway, a little SEO tutorial for the content editors can go a long way. You would be surprised what people who know thier products can come up with. I have seen great titles and URLs done by our content editors, that I would never think of in a million years from my position as a developer.