We've written about Allvoices, a citizen journalism platform that is seeing fast growth internationally. In fact, the site, which was launched in 2008, is even approaching CNN's iReport in terms of worldwide traffic. According to comScore's May data, Allvoices saw 3 million unique visitors worldwide compared to 3.6 million unique visitors for CNN's iReport. But in the U.S., CNN still has a huge market share of traffic. For the same time period, comScore reports 3.3 million unique visitors for iReport, with Allvoices only seeing 730,000 visitors in the U.S. in May. According to Quantcast, Allvoices saw 6.5 million unique monthly visitors in May. The site has also grown its registered number of citizen journalists to 375,000 users from 275,000 in January. CNN has just under 500,000 registered "iReporters."