SEGS (Search for Enriched Gene Sets) is a web tool for descriptive analysis of microarray data. The analysis is peformed by looking for descriptions of gene sets that are statistically significantly over- or under-expressed between different scenarios within the context of a genome-scale experiments (DNA microarray). You can find it here

Descriptions are defined by using the terms from the Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and gene-gene interactions found in the ENTREZ database. Gene annotations by GO and KEGG terms can also be found in the ENTREZ database.

The tool provides three procedures for testing the enrichment of the gene sets (over- or under-expressed): Fisher’s exact test, GSEA and PAGE, and option for combining the results of the tests. Becouse of the multiple-hypothesis testing nature of the problem, all the p-values are computed using the permutation testing method.

This web site is the accompanying part of the Igor Trajkovski’s PhD thesis, titled:
“Functional Interpretation of Gene Expression Data”.