AmiGO: the web interface for searching and browsing the Gene Ontology. The Gene Ontology project provides a controlled vocabulary to describe gene and gene product attributes in any organism.

BioGRID: BioGRID is a freely accessible database of protein and genetic interactions. Interactions are included from Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster and Homo sapiens.

BRITE | KEGG : collection of hierarchical classifications representing molecular interactions, and many different types of relationships, for inferring higher-order functions.

DAVID | NIAID: A set of functional annotation tools for investigators to understand biological meaning behind large list of genes. David includes the following tools:

1. Functional Annotation
2. Gene Functional Classification
3. Gene ID Conversion
4. Gene Name Batch Viewer

Ontology Browser | OBO Foundry: The Open Biomedical Ontologies (OBO) Foundry is an attempt to produce well-structured vocabularies for shared use across different biological and medical domains. The OBO Foundry strives for the establishment of gold standard reference ontologies for individual domains of inquiry.

Resources For Ontology Usage | SOFG (Standards and Ontologies for Functional Genomics): Resource for the development of ontologies and other controlled vocabularies relevant to biology and biological experimentation.