So...evidently posting that above just cursed me. After I wrote that, I rode my bike into work. I haver one very difficult intersection to cross. The problem is going from the road, past oncoming traffic and onto a bike path along the Charles River. The intersection is the site of many accidents - mostly automobile (knock wood).
My normal approach is to find a safe stretch of road, and then 'steal' a few yards of side walk on the opposite side to cross an easier intersection onto the bike path. Alas, today, I had a huge line of cars stacked up in the left hand lane, and a cop had pulled over a motorist in exactly my cut-over spot.
The second option, which I've seen bikers do, is to just stay in traffic and take a left hand turn with help of the traffic light. The traffic divides into a left-hand turn lane and a straight-only lane. There's pretty much no choice in that scheme, but to try to take a left, but it looks more treacherous to my eyes. When the light went green, I tried to pull out so as not to block the people going straight behind me, but maneuver to make a left safely once the on-coming traffic stopped. I left what I thought was ample room for the straight-only people to go by me, but boy! did it feel exposed.
Finally there was a gap in the oncoming cars and I made it onto the bike path. Phew. BUT, a guy in a pick-up drove by and said "Don't block the f**king traffic, a**hole!"
What can you do? There are just plain dangerous intersections - signal, make yourself visible, be patient, try to not obstruct anyone, but even then, that's no guarantee.