I ride a very traditional track geometry bike on the street, with a 75 degree head tube and a 75 degree seat tube.
However, before I discuss this any further, I suggest the reader visit Anvil Bikes' home page and click on "trail calculator."
http://www.anvilbikes.com/
This will download an .xls file that will allow the user to play with all the factors that determine trail, and this will give the user as complete an understanding of trail as one would want.
Continuing then, a steep head tube gives the rider "quick" steering, and a complementary short rake restores stability to that "quick" steering.
With my 75 degree head tube angle, 28.5 mm of rake/offset, and 25mm tires, I enjoy 60.5 mm of trail, which puts me right about in the middle of the industry standard range for trail (50 - 70 mm).
Returning to "track geometry," the steep seat tube puts the rider far forward on the bike and "opens" his thigh/hip joint for pedaling power, thus making possible a level-back aerodynamic riding position.
This level-back aerodynamic riding position, with so much weight on the arms, hands and front wheel does not lend itself to daily riding.
A person can accommodate him/herself to this riding position, but a more upright "on the horns" roadie-type of position really works better for long-term on the street, mixing with traffic and dealing with road irregularities.
However, a more upright "on the horns" position, in combination with a steep seat tube angle, makes the "cockpit" too short (or the center of weight too far forward), and so, in my case, I ride with a setback seat post.
Alternatively, many riders can "get by" just by sliding their saddle further back on a conventional seat post.
One might notice a trend in recent "track" bikes to a more roadie-type geometry (the 2009 Bianchi Pista now has a 73 degree head tube angle in place of the former 75 degree head tube angle).
I think manufacturers have done this in recognition of the Fixed Gear fad on the streets.
Designers can still create a head tube angle and rake that gives them a trail of around 60 mm, with only a few compromises.
I ride one fixed gear bike that has a 72 degree head tube angle and a much longer rake; I ride a second fixed gear bike that has a 75 degree angle head tube and a very short rake; and both bikes have a trail of 60 mm.
The two bikes, despite their common amount of trail, handle quite differently, and each type of handling has its virtues.
For example, the slack head tube and long rake bike deals with road irregularities much better than does the steep head tube and short rake bike.
And, comparatively, the steep head tube and short rake bike handles very nimbly, with delightfully stable agility.
Both bikes have the same trail.
However, the two bikes have differing degrees of "flop."
I'll let the reader figure out "flop" for himself, but, one could go to the following site for a program that shows "flop"
IF you know your true tire diameter (rim plus tire height).
http://kogswell.com/geo.php