<p>I've seen several products that will track the sales rank of an item on Amazon. Does Amazon have any web-services published that I can use to get the sales rank of a particular item? </p>

<p>I've looked through the AWS and didn't see anything of that nature.</p>

You should be able to determine the Sales Rank by querying for the SalesRank response group when doing an ItemLookup with the Amazon Associates Web Service.
Example query:
```
```
http://ecs.amazonaws.com/onca/xml?
Service=AWSECommerceService&
AWSAccessKeyId=[AWS Access Key ID]&
Operation=ItemLookup&
ItemId=0976925524&
ResponseGroup=SalesRank&
Version=2008-08-19
```
```
Response:
```
```
<Item>
  <ASIN>0976925524</ASIN> 
  <SalesRank>68</SalesRank> 
</Item>
```
```
See the documentation here:
http://docs.amazonwebservices.com/AWSECommerceService/2008-08-19/DG/index.html?RG_SalesRank.html