I didn't believe that cyclists actually ran red lights until I saw one do it right in front of me last week, whilst turning right on a busy crossroads of all places! He was somewhat taken about when I leant out of my truck window and shouted at him as loudly as possible:
"IT'S A RED LIGHT YOU F***ING IMBECILE, I HOPE YOU GET SYPHILIS AND DIE!"
And yes, they were my exact words. Not big, not clever, but the ***** deserved it.
I don't put many miles on my cycle myself but I am acutely aware of just how vulnerable you feel so I always give plenty of room and space when in a car and passing, and likewise when on the bike I always try and give plenty of warning when I want to change direction. I'm not perfect though, I know that, and I really wish that my bike had a rear view mirror and indicators as that would make my life so much easier/safer. There's no easy answer really, it just relies on common sense on the behalf of both parties, something which is getting less by the day sadly.