Any holder of the American Express Platinum Card (_not_ the Platinum Optima or whatever the revolving card is) can use the Presidents Club gratis (including two guests) when the cardholder is flying on Continental within 24 hours before or after the time of the visit. A similar benefit applies for the Northwest and TWA clubs. In my humble opinion, that benefit alone is almost worth the annual fee, although it's obviously somewhat more restricted than being a club member.
-Adam