Top-Level Categories - John F. Sowa's top level categories. Just categories (no relations) but still representative of what a top level ontology resembles to.
The Generalized Upper Model 2.0 - A general linguistically motivated ontology. It has been conceived as a standardized top level ontology for NLP applications.
A Top-Level Ontology - A top level ontology which combines the Frame-Ontology from Ontolingua, some parts of CYC upper layer/Generalized Upper Layer Model and merges these with WordNet.