Wikipedia
BioNumbers is a free-access database of quantitative data in biology designed to provide the scientific community with access to the large amount of data now generated in the biological literature. This aims to make quantitative values more easily available, to aid fields such as systems biology.
The BioNumbers project performs literature-based curation of various sources. It is a regularly updated online resource that contains >6,000 entries from ~1,000 distinct references. Examples of data include transcription and translation rates, organism and organelle sizes, metabolites concentrations and growth rates. Entries are provided with full reference and details such as measurement method and comments. BioNumbers also publishes a monthly review of a problem in quantitative biology.