Expression Connection allows you to search gene expression data from multiple microarray studies.
Search I: Find the expression of one or more genes in one or more datasets.
Search II: Find datasets where the expression of one or more genes changes by an amount you define.
Search III: Find all genes that change expression in a manner you define in one or more datasets (eg. increase by 10-fold).
Other Expression-Related Resources:
Webminer: Search microarray datasets on an experiment by experiment basis.
External Resources
SPELL (Serial Pattern of Expression Levels Locator): A query-driven search engine for large gene expression microarray compendia. Given a small set of query genes, SPELL identifies which datasets are most informative for these genes, then within those datasets additional genes are identified with expression profiles most similar to the query set.