The Perseids are one of the more dependable meteor showers still averaging a shooting star every minute at their peak even 15 years after the comet has passed. The Perseids are probably the most-watched annual meteor shower.

These meteoroids are particles shed from the comet that follow it's orbit around the solar system. They are no bigger than sand grains or pebbles, have the consistency of cigar ash and are consumed many miles above our heads, so you don't have to be worried about getting hit. Perseid meteoroids are exceptionally fast, entering Earth's atmosphere at roughly 133,200 mph (37 miles per second) causing the long trail.
(Note: This speed is a combination of the earth's speed around the sun [67,122 MPH] and the particles speed coming toward us, since the comet goes around the sun in the opposite direction of the earth.)

The shower begins, gently, in mid-July when Earth enters the outskirts of a cloud of debris from Comet Swift-Tuttle. The Perseids are considered active from about July 25 through Aug. 18, though hourly rates usually do not rise above 10 until about Aug. 8. Rates fall off much more rapidly after the peak, dropping again to below 10 per hour after about Aug. 14.

Expect 40 to 60 meteors per hour, some of them bright, when it peaks on August 12th, although in any given year concentrated bands of particles may be encountered on the 11th or 13th. Early morning hours are best, astronomers say, because the part of Earth on which you stand is then facing the oncoming debris as the planet plunges through space on its orbit around the Sun. Experts suggest going out around 2 a.m. and staying until dawn breaks.
If this is too early for you, try looking east at 9 or 10 p.m. on Aug. 11th when Perseus is hanging low in the eastern sky. You won't see many meteors then, but the ones you do see could be memorable. Shooting stars that emerge from the horizon and streak horizontally through the atmosphere are called "Earthgrazers." Slow and colorful Earthgrazers are a good target for city dwellers, because they are so bright.

As Earth rotates, the side facing the direction of its orbit around the Sun tends to scoop up more space debris. This part of the sky is directly overhead at dawn. For this reason, the Perseids and other meteor showers (and also random shooting stars in general) are usually best viewed in the predawn hours.

See a Sky Map for Clair Tappaan Lodge / Donner Pass, Soda Springs, CA

There might be an extra surge of meteors on August 11th caused by a filament of dust newly (since 1862 passing) drifting across Earth's orbit. Most of the cloud is older (perhaps thousands of years old).

Technically, the peak occurs in the afternoon of Aug. 12 in North America. Meteors can only be seen at night, however. The best views will come late Aug. 11 into the early hours of Aug. 12.

The radiant for the Perseid meteor shower is a point near the border between Perseus and Cassiopeia, down and to the left from the familiar W pattern of Cassiopeia. During this shower, meteors can be seen anywhere in the sky, but they will all appear to be moving away from the radiant.
Meteors enter the earth's atmosphere over a large area, but they begin to burn up so far above the observer that their trails seem to lead back to one common point, just as parallel railroad tracks seem to meet at the horizon.
Lay back on a blanket or lounge chair and scan the entire sky. It is customary to watch the point halfway between the radiant (which will be rising in the northeast sky) and the zenith (straight up), though its all right for your gaze to wander.
See Sky Map for Clair Tappaan Lodge / Donner Pass, Soda Springs, CA

Perseid meteors are typically white or yellowish with some glowing trains and an occasional very bright meteor called a fireball.

If you are clouded out on the morning of the 12th, rates on the 13th will also be impressive, much better than those seen the day before maximum.

For Europe, the peak comes near or soon after midnight on Aug. 13.

(Note: Perseids favor northern latitudes. Because of the way Comet Swift-Tuttle's orbit is tilted, its dust falls on Earth's northern hemisphere. Meteors stream out of the constellation Perseus, which is barely visible south of the equator.)

Up to 10 shooting stars per hour not associated with the Perseids grace the sky this time of year. These other meteors can approach from any direction in the sky.

There is a more technical description at the International Meteor Organization 2007 calendar (imo.net) which states:
The Perseids were one of the most exciting and dynamic meteor showers during the 1990s, with outbursts at a new primary maximum producing EZHRs (Equivalent Zenithal Hourly Rate) of 400+ in 1991 and 1992. Rates from this peak decreased to ~ 100-120 by the late 1990s, and in 2000, it first failed to appear. This was not unexpected, as the outbursts and the primary maximum (which was not noticed before 1988), were associated with the perihelion passage of the Perseids' parent comet 109P/Swift-Tuttle in 1992. The comet's orbital period is about 130 years, so it is now receding back into the outer Solar System, and theory predicts that such outburst rates should dwindle as the comet to Earth distance increases. However, some predictions suggested 2004-2006 might bring a return of enhanced rates ahead of the usual maximum, and in 2004 a short, strong peak happened close to that anticipated pre-peak time. After that, activity seemed to be roughly normal in 2005, and the moonlit 2006 return was still to come when this text was prepared, but nothing untoward was predicted for 2007 in any case. An average annual shift of +0°05 in the λ* of the "old" primary peak had been deduced from 1991-99 data, and allowing for this could give a possible recurrence time around 9h UT on August 13 (λ = 140°16), if so a little after the most probable maximum, that of the "traditional" peak always previously found, which is given above. Another feature, seen only in IMO data from 1997-99, was a tertiary peak at λ = 140°4, the repeat time for which would be 15h UT (7 PM PDT) on August 13. Observers should be aware that these predictions may not be an absolute guide to the best from the Perseids, and plan their efforts accordingly, so as not to miss out, just in case!

* λ - ecliptic longitude in degrees east from the vernal equinox.

Links and Sources for the above:
See Sky Map for Clair Tappaan Lodge / Donner Pass, Soda Springs, CA
Perseid Meteor Shower and Watching, Counting and Photographing the Perseids at Space.com
NASA story on 2005 Perseid at science.nasa.gov
Swift-Tuttle orbit at jpl.nasa.gov
Animation at Exploring Earth
Viewing Tips at StarDate.org
Other Meteor Showers