Over the past two decades, the trickle of data emerging from DNA sequencing projects has increased to a flood. For example, by early 2003 there were over 36 billion bases of DNA sequence publicly available. New molecular marker technologies have similarly resulted in a huge increase in the availability of detailed genetic maps of model organisms and crop species. These advances have necessitated the development of bioinformatics tools for curation, dissemination, analysis and comparison of genome data, facilitated by the pace of improvement in computing power and storage capacity. Many genome databases use the object-oriented ACEDB database management system. ACEDB offers powerful search tools and sophisticated cross-linking between data items, and has tools to facilitate comparative map and sequence displays. Because many crops, including most forages and turf, have large genomes they are unlikely to be sequenced in the near future. However, comparative genomics offers breeders many opportunities for targeted molecular breeding approaches, and there are now several major of comparative plant genome bioinformatics projects worldwide. Bioinformatics can assist in development or selection of markers associated with quantitative traits, and identification and cloning of candidate genes for control of important characters. Post-genomic techniques such as transcriptomics and metabolomics, which can aid characterisation of mapping populations and varieties, also require bioinformatics tools for the curation, analysis and displaying of the very large data sets which they can generate.