I'm going to maintain a master list of discount real estate brokers in Ottawa. These brokers can list your house on MLS for a flat fee. Typically a small fraction of what a full service broker would charge you. Note that you still have to offer a commission to the buyer's agent. 2.5% is the current norm in Ontario.
I will update the list as more brokers switch over from the dark side
1. Best Value Real Estate
I believe he was the first broker in Ottawa (if not entire Canada) to offer a flat-fee MLS listing. The Ottawa Citizen called him "the most hated realtor in Ottawa". He used to charge $109 for a flat-fee MLS listing. The web site no longer shows the fee, so I'm not sure what he charges now.
2. Equity One Real Estate
$495 flat-fee MLS listing.
3. Wiktor Realty
$495 flat-fee MLS listing.
4. Ziglu Real Estate Brokerage
$500 flat-fee MLS listing.
5. The Usher Group
The web site doesn't list the fee. I heard they charge a flat fee in the $300-$400 range, but this requires verification.
6. Flat Fee Realty
$995 flat-fee MLS listing.
7. MVA Capital Realty
$500 flat-fee MLS listing.