UK (which for census purposes includes the Isle of Man) is subject to 100 year rule.
The 1911 census will be available January 2012.

If you have the name of at least one party and the year you should be able to get a marriage certificate from the Registrar General in Douglas.
I understand they will search for two years either side of the year you provide.

If you have only a very vague idea of the date, you could get the Index microfilm through any LDs centre. For this period the index should be cross referenced and will name both parties.

The marriage certificate will show the previous married name and maiden name for a widow.