Along with electing Kerry, I think the best we can do to support significant change is to take back the house and senate. My congressman, Howard "Buck" McKeon has had a pretty safe 10 years in Congress. No one has come close to challenging him. If you don't know who he is, you can find out more here:
http://mckeon.house.gov/Now might be the time. While the district overall has been safe for Republicans, that has been changing as we continue to grow, taking more and more of the overflow from the Los Angeles area. Palmdale now has a democratic majority, and, to the ever-lasting shame of the rest of the AV, went for Gore in 2000.
He has an interesting challenger this year, Fred "Tim" Willoughby. You can find out more about him here:
http://www.willoughbyforcongress.com/Our small local dem club is campaigning for him. Any support from other Californians is greatly appreciated!