UPDATE: CrunchBase have now restored their own documentation so you should now use the canonical information at http://developer.crunchbase.com/. I am leaving this here in case of existing links to it but it is of historical interest only.
NOTE: This documentation has been put here because I couldn't find it anywhere else. I am not associated with Crunchbase in any way. I cannot help you with your Crunchbase API problems. If you need help try here: https://groups.google.com/forum/#!forum/crunchbase-api