From Legacy Wiki
The overall Number of Accounts on Legacy can be found in the bottom left hand corner of the page when you login. This number changes gradually for better or for worse daily, because accounts are constantly changing (a result of the fact that accounts are created and deleted every day).
The number of accounts on January 19, 2011 was approximately 1602 (subject to change daily).
The number of accounts has been over 3000 (March/April 2006) but the main reason for this was that the delete script for inactive accounts didn't work.
As of August 11, 2010 :
There have been 19,195 total signups since May 28th 2005.
On 13 September 2009 the total number of accounts accounts was around: 2741.
On April 27, 2010 the total number of Legacy accounts was 1940
On August 11, 2010 the total number of accounts was 1943.
Increasing the Number of Accounts
One of the main things that helps the number of accounts increase is voting on game sites. As more and more players vote for Legacy, the ranking of Legacy rises on gaming sites, making Legacy more publicized. Another way to bring new players into the game is to refer players. Simply talking to people about Legacy will perk their interest and they might sign up! So spread the word!!
You can complete achievements by referring people, so why not earn some?