Air Canada has introduced a variety of passes (only available to Canadians, so choose the Air Canada Canadian site for details) that offer a set number of flights for a discounted price. Today, the airline has announced the Spring Sample Pass, which offers flight passes for as low as CDN$99 (US$85) per flight.
Air Canada has introduced some pretty innovative fare concepts in the past couple of years, including a major overhaul of its regular pricing to offer only a handful of fares on each flight. However, in both that initiative and in this pass program, they have made the restrictions somewhat complicated. By "somewhat" I mean "extremely." (For extra credit, explain the difference between the 5 fare classes, paying special attention to the differences between "Latitude" class and "Tango Plus." See here for the details.)
Basically, the $99-per-flight pass is available for flights within Western Canada on 4 offpeak days per week. Other passes allow you to fly within or between other regions either 4 days a week or 7 days a week (all of this is explained at aircanada.com. There are some restrictions on earning frequent flyer points, but the restrictions are so long that I can’t be bothered to figure them out.
That all said, most of the passes are a pretty good deal, but pay attention to the fine print. Even so, I applaud their innovative thinking.