actually, there are 6 top level facets in TechFinder: here's a view of this from a dev environment page.

http://dev.techsoup.org/techfinder_v1/unskin/index.cfm?p=browse_ng_2&tftaxid=68&tftaxid=8#b

David's right that it is a faceted approach, but TechFinder's taxonomy is designed to be deepened, for example you can see under Consulting in the above url, that 2 subelements, Organizational Development and Tech Planning are listed there. No deeper levels have been developed yet, and none have been suggested.