MaizeGDB (the Maize Genetics and Genomics Database) is the research database for the maize community. The site features a wealth of resources and data facilitating the scientific study of maize. Among the data sets included in MaizeGDB are sequences, including PlantGDB's EST and GSS contig assemblies; references; detailed genetic, physical, and cytogenetic maps; primers; and various other datatypes. MaizeGDB includes integrated tools for map comparisons, sequence similarity searches, and links to other databases, such as Gramene and NCBI. MaizeGDB provides web-based community curation tools that enable researchers to edit and annotate their own data and to enter new data into MaizeGDB directly. MaizeGDB also provides informatics support for maize community initiatives such as the Annual Maize Genetics Conference and community-wide workshops, and maintains data for maize community research projects. MaizeGDB is funded by the USDA-ARS and can be accessed online at http://www.maizegdb.org.