writes "Biologists estimate that about 1.75 million species, from bacteria to blue whales, have already been identified on Earth. But there may be anywhere between 3 million and 12 million more yet to be discovered. An online catalogue of all known life on Earth now has half a million species in its freely available database. Another promising effort is Wikispecies. Started in August 2004, this is an offshoot of the Wikimedia group, whose free online encyclopaedia is constructed by users themselves."
(And Wikipedia itself
is about to publish its 500,000th English entry -- if you hurry, perhaps it will be yours.)