Some people have felt that switching graphics modes is the source of Mavericks crashes. I had five crashes in several days last week. I went to the Energy Saver control panel, and turned off Automated Graphics Switching. Haven't had a crash in a week. Could easily be coincidence, but I thought I'd mention it here in case anyone else wants to try it. I'd be very interested in hearing whether it helps.
By the way, what happens on my machine is that the UI completely freezes. I'm not sure if that's what other commenters experience when they talk about "crashing".
No crashes or kernel panics since then, but I agree that switching graphics modes seems to cause most of my crashes. I get the "rainbow crash" where the UI freezes and garbage appears in stripes and blocks on the screen. I can still ssh into my MacBook and reboot it (or even restart the UI, I think).
By the way, what happens on my machine is that the UI completely freezes. I'm not sure if that's what other commenters experience when they talk about "crashing".