I think I'm getting used to being a cycle commuter in London. The rules are really quite simple - trust nobody, assume everyone in a car is going to be a psychopath and every pedestrian is going to run out in front of you, and obey traffic laws. I know the latter is controversial, but I have no choice but to utterly reject a lot of the bleating from various cycling pressure groups in London until I can be convinced that most of the cyclists who get injured or killed in London are actually obeying the law at the time. I see too many cyclists jumping red lights straight out into intersections and generally behaving suicidally to think otherwise. The first thing you should do if you want to be treated seriously as a road user is behave like other road users are expected to and as the law requires rather than somehow considering yourself a special case to whom those funny coloured lights have no relevance.
Sorry, bit of a rant there. I know that drivers regularly cut you up, or park in bike lanes, or occupy the bike boxes at traffic lights (and take note, motorcyclists, that's a picture of a pushbike in that box, not a motorbike). That's no excuse for cyclists not to set a good example, though, and until that starts happening I prefer to distance myself from the cycle lobby somewhat. There are sane cycling organisations out there - kudos, for instance, to the CTC for doing sensible things like defending the guy who got fined for cycling on the road. But I digress.
I may complain about light-jumpers, but there's one really big pleasure in bike commuting, and that's reeling in and overtaking them after the lights change. A lot of the time this happens quite quickly as they're wobbling along at a fairly constant pace, but speed demons can be a bit more tricky. After a couple of months of regular cycling I'm able to cheerfully pass people on bikes more expensive than mine quite often now, which always produces a warm, fuzzy feeling. And that's with a heavy rack and a pannier on the back carrying my work stuff, which adds a few kilos to the weight of the bike - I should work on ways of reducing the weight I have to carry in order to make my commute more pleasant.
The other activity nobody should miss is riding through London in the dead of night. In the small hours there's virtually no traffic and very few people around, so you basically have the capital's wide roads to yourself. Great fun, and makes for some rather speedy journey times. However, this also brings home just how terrible a state some roads are in - I recommend avoiding, for instance, Oxford Street as it's more potholey than I thought was possible for a non third-world country. This is easily countered by stretches of clear, wide road like the Victoria Embankment late at night and the Mall at, well, most times of the day - there's a reason the Tour of Britain's finishing sprint was held on the latter. I can recommend hitting the drops and stamping on the pedals in a nice high gear for this one, but you have to keep your fingers crossed that you won't get stopped at the pedestrian crossings or other lights en route. If you do, just look casual and pretend you're doing intervals.