Right now I only have two - my IGH/front-back racks/panniers/full fender utility bike for most commutes, and a road bike with raceblades/backpack for the "ohcrapIoverslept" commutes.

But I could justify SO MUCH MORE.

I want:
A folder, for when I have to travel.
A fat bike, for snow (it only snows like 2x a year here and is usually melted in an hour, ha ha)
An MTB with studded tires, for ice.
A CX bike so I can take routes that involve some dirt and some pavement.
A long-tail cargo bike/bakfiet/BAW trailer for when I have to do some serious haulin'.

Give me some time, I'm sure I could think up more. And this doesn't include bicycles I want just because they'd be fun to ride, like a TT or a track bike.