Getting by with few bikes

As a father with one kid a freshman in college, and the other a freshman in high school, I'm looking at 7 more years of extreme college expenses and years of paying PLUS loans to follow.  Like many cycling enthusiasts, I yearn to have a stable of bikes, each with its own specific purpose. The way I figure it, I need 8 bicycles to meet my most basic needs.  In order of importance, these are:

1. The comfort road bike.  This bike is exemplified by the Specialized Roubaix.  For long hours in the saddle such as weekend solo rides through the countryside, this ultra light bike with a set of lightweight climbing wheels gets the job done in comfort.
2. The aero road bike.  Pioneered and best exemplified by the Cervelo S5, the aero road bike is the stiff, fast, light machine for the fast group ride on the weekends.  Grinding your friends into submission on long pulls and sprinting for town signs, the aero road bike is the tool for the job.
3. The cyclocross bike.  When fall rolls around and the road season ends, road cyclists aren't yet ready to hang up their wheels.  It's time for 'cross season.  The cyclocross bike is a drop bar road bike with beefier wheels and more wheel clearance for mud.  Also, mountain bike pedals are used instead of road pedals for quick mounting and dismounting.  I like my Norco, so here is their top end example.    
4. The time trial bike.  You may know these as triathlon bikes, these are either super dorky or super cool depending on your point of view.  The time trial bike is built for maximum speed in the individual timed effort.  Everything, including comfort takes a back seat to aerodynamic efficiency in this category.  Once again, Cervelo typifies the breed with the very successful Cervelo P3.
5. The track bike.  I gottsta have a track bike.  Riding the old ill fitting club bike simply sucks.  I'm a sprinter/jumper by genetics.  Being big and strong with fast twitch muscle means the track bike features big in my priorities.  Track bikes are fixed gear, no brakes, and with aggressive geometry once again prioritizing handling precision and speed over comfort.  A Veloforma Pista Pro seems about right to me.
6. The short trip cruiser.  Don't want to put on cycling shoes for a trip to the grocery store?  Riding around the block with the kids?  Imagine how ridiculous you would look on the time trial bike!  You would only look slightly less ridiculous on any of numbers 1 through 5.  No, you need to have the short trip cruiser.  This bike should be upright, comfortable, and with a simple platform pedal suitable for any type of shoe. 
7. The mountain bike.  OK, so even a dedicated roadie needs a mountain bike, and possibly many.  Since this is a minimal list, and not a dream list, I stick with the "cross country" bike.  These are all around machines designed for traveling long distances off road through a variety of terrain.  They are lighter weight than the purpose built down-hill bikes, for example.  At the risk of sounding like a Specialized bigot (I don't own any Specialized bikes), the classic Stumpjumper is a good example of the breed.
8. The commuter bike.  Last place?  How is it that the bike that will be ridden the most, and relied upon to get you to and from work on a daily basis be the last on the list?  The reason is really that a few of the other bikes can be made to function as a commuter.  More about that in a moment.  Bikes designed specifically for high speed, performance commuting are a relatively recent phenomenon, although they have a lot in common with the traditional touring or randonneuring bike with fenders.  The Trek Portland is an early example, though the spec was steadily dumbed down throughout its life and finally discontinued due to being insanely overpriced for the spec.  The Kona Honky Inc is a good example of a smart spec, but needs fenders and lights added after the fact to be functional as a commuter. 

I don't have 8 bikes.  So in order to do all of the cycling activities I want without owning 8 bikes, I need to make a single bike work for many purposes.  For this, it means using a standard road race bike as a daily commuter.  The first product that makes this possible is the SKS Race Blade Fenders.  These things make no noise, stay in place, and keep me dry.  Best of all, they go on and off in minutes with no hardware required.  The second thing needed is a good set of lights.  I don't have anything special for the headlight.  That's an investment I need to make.  Currently I have an el-cheapo blinking LED white light that uses AA batteries.    I'd really like to call your attention to this little guy, the Serfas TL-ST.

Made of silicon, it wraps around the seat post or seat stay and gives amazing light.  The battery is still going strong after many hours of night time flashing on my commutes.  It's minimalist, functional, efficient, and inexpensive.  Sure, the road bike sees way more dirt, grit, rain, and grime than most.  But until I hit the lottery and can buy all 8 bikes I need, the road bike has to serve many purposes.