You can get the AMEX Platinum Card (Not Aeroplan) which gives free Companion Tickets as part of its International Airline Program (IAP). I dont believe there are any limits to the free companion tickets. However there are date and class of service conditions depending on airline.
Participating airlines are: Air France, Air New Zealand, Austrian, Continental, Japan and Swiss.
The card also offers special airfares with Singapore Airlines (30% discount in business) and Alitalia (30-55% discount in business)
You can transfer membership reward points into aeroplan.
Card fee is $399 and actually looks better than the aeroplan plus platinum card.