I'm keeping up with traffic on El Camino Real in this video, but passing to the left also works for slow cycling when traffic conditions warrant. Signal, check back and merge over when it's safe.
If I'm following a bus and I know the bus is just pulling over for a passenger pickup, I've been known to hop up on the sidewalk and pass on the right. The problem with this is that if the bus is stopping for passenger pickup or dropoff, that means there are people on the sidewalk (*doh!*)