NCBI's Map Viewer provides special browsing capabilities for a subset of organisms in Entrez Genomes. Map Viewer allows you to view and search an organism's complete genome, display chromosome maps, and zoom into progressively greater levels of detail, down to the sequence data for a region of interest. If multiple maps are available for a chromosome, it displays them aligned to each other based on shared marker and gene names, and, for the sequence maps, based on a common sequence coordinate system.

Ensembl [Hubbard et al. 2007] is a joint project between EMBL - EBI and the Sanger Institute to develop a software system which produces and maintains automatic annotation on selected eukaryotic genomes. The Ensembl project aims to provide: (1) accurate, automatic analysis of genome data, (2) analysis and annotation maintained on the current data, (3) presentation of the analysis to all via the web, and (4) distribution of the analysis to other bioinformatics laboratories.

Ensembl concentrates on vertebrate genomes, but other groups have adapted the system for use with plant and fungal genomes.

The UCSC Genome Browser website [Kent et al. 2002] contains the reference sequence and working draft assemblies for a large collection of genomes. It also provides a portal to the ENCODE project.

The Genome Browser zooms and scrolls over chromosomes, showing the work of annotators worldwide. The Gene Sorter shows expression, homology and other information on groups of genes that can be related in many ways. Blat quickly maps your sequence to the genome. The Table Browser provides convenient access to the underlying database. VisiGene lets you browse through a large collection of in situ mouse and frog images to examine expression patterns. Genome Graphs allows you to upload and display genome-wide data sets.