Twitter analytics and ads have been opened up to all users. Although it's still only possible to advertise to users in the US the analytics is a great new tool for all businesses and power users, even if they don't advertise. The analytics shows the number of RTs, replies and favourites for every tweet and tweets can be ranked by 'Best', 'Good' and 'All' to see what tweets get the greatest response from followers. It's available via ads.twitter.com.