eBay's full taxonomy list
We have compiled the full eBay US taxonomy in this CSV file:
If you want more information regarding a particular category, such as whether it supports multi-variations and what item specifics can be specified, there is a free tool available.
Browsing categories on eBay.com
Below are a few links to the eBay categories and their IDs
Also, remember when browsing eBay itself, the URL for category navigation contains the category name and ID. "162926" is the category id for Barn Doors and can be found in the URL for the category landing page. For example http://www.ebay.com/sch/Barn-Doors-/162926/i.html