Since going national last fall, it has doubled its membership, to nearly one million.

LinkedIn is growing at breakneck speed, almost doubling its membership to more than 90 million users last year in 200 countries.

Scouts Canada has begun a process with the goal of doubling its membership by 2014.

After 1930 Hitler's party doubled its membership every year because of the economic crisis.

By its second year, the Ubiquiteers doubled their membership to 62 students from 23 countries.

The society, which is campaigning against bacon and eggs as "the breakfast of cruelty," has doubled its membership in five years to 525,000.

But they have recently regrouped and are expanding rapidly, doubling their membership to about 2,000 men over the past decade, law enforcement officials say.

He said if everybody recruited a friend to the Labour party, we'd double our membership.

He was successful in doubling the church's membership during his time, from 1900 to 3600 people.

"The bottom line is, nobody has any unrealistic dreams of doubling our membership in one year," he said.