Avalanche Responsible for Most Phishing Attacks
An East European gang has been found to be responsible for more than 50% of the phishing attacks during 2009 - specifically 84,000 out of 127,000 attacks. The gang was named Avalanche because of the vast quantity of attacks they can generate. They use sophisticated technologies to launch focused attacks on lucrative targets like the big banks.
They are elusive, too, because law enforcement agencies have been tracking their activities for years, but haven't been able to do anything about them. Here's an article on them.