Google Earth for Landscape Photography I have not found anything for better then Google Earth for simulating how the light on the land falls at different times of the day and year. It will show you shadow detail near sunrise and sunset where the sun will appear or disappear. Consider it a great scout for larger geoligical features which really helps you create that backdrop before Iyou even show up.
Weather Satellite Radar Clouds can be scarce in California so this a great tool that goes beyond look out at the sky from my front yard. With the radar I know what is coming beyond the horizon all though things can change only minutes after leaving the house it helps a photographer evaluate his situation. Don't let the radar keep you at home if things don't look and want to get out there. Example 1 • Example 2
California Coast Line is a series of aerial views that span the California Coast from the mexican border in the south all the way up to the California Oregon border. It really helps me find interesting scenes that are far from iconic.
The Photographer's Ephermeris Do not let those high mountains steal your sunset an hour before you estimated it would be. This tool helps you find out where the sun and moon will rise and set and you can even load an application into your cell phone. The terrain feature helps find out when the sun will set early due to high mountains blocking the actual sunset that happens later.
Carol Leigh's CalPhoto.com Wildflower and Fall Color Hotsheet. (Site down due to disregard for private property 3/30/10)
Finding a source that is up to date for spring wildflowers and fall color in your area is a great tool and increase your chances of getting there at peak season. If you are not in California most states / provinces usually have something similar or even multiple sites that can help you find what you are looking for. Just keep in mind the greater the elevation change you have the longer your season will last. Here in Southern California fall ends and spring can start in only weeks. In the rest of California you can find either one or other, something blooming or leaves changing color during anytime of the year.