There's a difference between 'forced' and 'legally compulsory'. Thankfully there are few countries in the world where they will march you to the voting booth and force you to vote. There are a lot more countries where if you don't vote there is a legal remedy available to the state (fine, imprisonment, etc).

I've been told Australia is one of countries where voting is legally compulsory - I'm sure pulse will confirm. In New Zealand there is a roll of voters, and you are legally required to register to vote, but voting itself is voluntary.