Yeah, I don't need one. I live downtown so the metro/bus system gets me everywhere. I'd like to bike to work, but the lack of showers at work is the deciding factor. Need to do some more research on it for next summer, and I'd probably get a 'proper' bike if I did it a lot. Bixi is rad because on a stinkin' hot day I can just grab a bike and ride home rather than being stuck in the metro smelling other peoples armpits.
Money saved on car registration/maintenance/parking etc means I can just rent a car for shred or DH missions. There's enough of us that we can split the costs and it works out well. Plus you can thrash the cars through the snow and not care :) There's actually a communal car rental system similar to Bixi, but I did the maths on costs and it's not actually much cheaper if you're doing a longish drive to go shredding/biking. I am really impressed with Montreal's ability to embrace options other than the car for transport. Then again, if you've driven in this city you'd understand why!