Fifty genomic gene expression studies of free living soil nematode C. elegans have been published. These include spotted microarray, Affymetrix chip, and SAGE datasets. Access to this data is limited by its scattered location and different data formats. To facilitate exploratory analysis of the gene expression data in C. elegans, we collected the raw data and constructed a gene expression database containing all the published C. elegans expression datasets. A Perl CGI program allows gene expression clusters of any combination of entered genes and expressions datasets to be viewed (http://elegans.uky.edu/gl/madisplay). Three hundred lists of genes from figures or tables in the published gene expression studies were extracted from the publications and made available in the GeneLists database. This database links each list to the cluster expression viewer. The GeneLists database also contains GO and KEGG gene lists. We used these tools to examine in a systematic fashion the mean expression gene lists in the set of C. elegans microarray experiments. Seventy-nine percent of publication derived gene lists show a strong expression change (p-value <0.001) in more than one experiment with the median being 14 out of the 128 experiments derived from the fifty publications. This indicates that groups of genes identified in one publication typically show an expression effect in many other experiments.