Using Browse Nodes
Amazon.com (like all the Amazon sites) organizes it's web pages using "browse nodes." A browse node originally represented a specific page at Amazon.com, but is now used most often to create a category of related products.
A "browse node ID" is used to identify a specific browse node. The ID is an integer value. There's no pattern to these numbers other than that each browse node has a unique ID. Browse node IDs are used by the BrowseNodeLookup and ItemSearch operations of Amazon's E-Commerce Services.
You can find browse node IDs in the A2S documentation and by looking at URLs at Amazon.com. But an easier way is to use the web site BrowseNodes.com (http://www.browsenodes.com/). BrowseNodes.com allows you to search for browse nodes, get information on each node, and download data on browse nodes.