Most online virtual worlds don't let you live a virtual life with a job, mayor, prime minister and the constant threat of invasion, but one game begs to differ. Erepublik is the virtual browser game with it's own economy and society complete with politicians, military and real towns and cities. It's the "biggest online historical experiment", complete with beta status.
I've been playing the game since April, and I have to say it is nothing like any other game i've played. It is more realistic, and best of all like any good game is completely free. Find a job, train for the day, or even start your own company - the possibilities with Erepublik are quite literally endless and limitless.
eRepublik: http://www.erepublik.com/