When you hear of a fatality on one of the routes you frequently take, that at least gets your attention and makes you think for a bit. Saratoga Gap/Highway 9, Montebello, and the Palo Alto loop around PageMill/Arastradero all have had fatalities in the last couple years or are an accident waiting to happen. I had a coworker killed in Sonoma last year while cycling and that didn't help matters much either.

Makes you at the very least think of your own mortality.

Another unnerving thing I occasionally see when riding are the memorial flowers/crosses on the side of the road in some windy areas. Usually not cyclists, though, but still creepy.