There's actually a surprisingly lot you can do with an airplane to earn money without an AOC.
You have to start in the Aeronautics Act and look at definitions.
commercial air service means any use of aircraft for hire or reward;
hire or reward means any payment, consideration, gratuity or benefit, directly or indirectly charged, demanded, received or collected by any person for the use of an aircraft;
Now the CAR's
aerial work means a commercial air service other than an air transport service or a flight training service;
air transport service means a commercial air service that is operated for the purpose of transporting persons, personal belongings, baggage, goods or cargo in an aircraft between two points;
flight training service means a commercial air service that is operated for the purpose of conducting flight training;
700.02 (1) No person shall operate an air transport service unless the person holds and complies with the provisions of an air operator certificate that authorizes the person to operate that service.
(2) Subject to subsections (3) and (4), no person shall, unless the person holds and complies with the provisions of an air operator certificate that authorizes the person to do so, operate an aeroplane or helicopter to conduct aerial work involving
(a) the carriage on board of persons other than flight crew members;
(b) the carriage of helicopter Class B, C or D external loads;
(c) the towing of objects; or
(d) the dispersal of products.
(3) A person who does not hold an air operator certificate may conduct aerial work involving the dispersal of products if
(a) the person is a farmer;
(b) the person owns the aircraft that is used to disperse the products;
(c) the products are dispersed for agricultural purposes; and
(d) the dispersal of the products takes place within 25 miles of the centre of the person’s farm.
(4) A person who holds a flight training unit operator certificate may conduct aerial work involving the carriage of persons other than flight crew members on board a single-engined aircraft if
(a) the pilot-in-command is the holder of a valid flight instructor rating in the appropriate category of aircraft;
(b) the aircraft is operated in day VFR flight;
(c) there are no more than nine passengers on board; and
(d) the flight is conducted for the purpose of sightseeing operations.
(5) Despite subsections (1) and (2), a person who does not hold an air operator certificate may operate an air transport service, or operate an aeroplane or helicopter to conduct aerial work involving the transport of passengers or goods, if
(a) the person holds a private operator registration document;
(b) the person operates the air transport service or conducts the aerial work under a management agreement with another person who has transferred to that person legal custody and control of the aircraft used to operate the service or to conduct the work;
(c) the management agreement provides that the air transport service is operated or the aerial work is conducted exclusively in support of the activities of the person who has transferred legal custody and control of the aircraft; and
(d) no payment is made in relation to the air transport service or the aerial work to a party to the management agreement by or on behalf of a passenger or the owner of a transported good unless the passenger or the owner is the person who has transferred legal custody and control of the aircraft.
So in summary, you can operate a commercial air service, without an AOC, doing aerial work only, as long as what you do is not in the list in 700.02(2). Basically, don't take people or their cargo. Things like aerial photography, spotting, prospecting, etc. are all legal. You could even operate a store out of your airplane by flying stuff to reserves and selling it.
There's also a lot you can't do. Offering sightseeing flights, "splitting" the cost of a flight, flying potential customers to look at properties, giving "free" flights to customers, etc.
