a) Lane switching cyclists who think no-one else filters but them.
b) Scooterists - as above
c) Lobotomised pedestrians who think nothing is coming from the right when they cross stationary traffic to the centre of the road.
d) Tourists doing U turns when sat-nav tells them there is a "quicker" way
I add:
e) stopped traffic (especially trucks & buses) letting somebody turn left/ right without checking their mirrors for oncoming bikes.
f) people pulling out (see e above) without checking for oncoming bikes. (Mate of mine has just trashed his MV Agusta & his thumb in a 5mph spill in exactly these circumstances)
g) pedestrian foreign tourists who look the wrong way
h) anything with "addison lee" written on it
i) any BMW over 5 years old never indicates (I know exactly where I'm going so no need to indicate syndrome)
j) Horse manure from mounted police
k) gravel dropped by lorries that always ends up in the middle of the road
l) London yoof walking straight out because they are so 'ard that a big feckoof bike won't hurt
m) people throwing lit fag ends out of windows / gobbing out of windows / pissing out of windows / opening beer cans out of windows
n) people handing out free copies of the sun in the middle of the road
o) people trying to play chicken with you filtering in the opposite direction, ie towards you when there isn't enough room for both of you.
p) Big issue sellers
q) School run mum trying to finish Tarquin's art homework and pack Fontelroy's packed lunch and do her makeup and organise lunch on the phone at the FerkinYummyMummy
r) Dogs jumping out of open car windows (seriously, it happens)
s) People running from the Fuzz
t) The Fuzz chasing after people
u) Squeegie bottle immigrants at traffic lights
v) Bike-jackers jumping on the back seat and telling you to get off of get stabbed (ok not so much in London)
w) dick'eds changing lanes using the "manoevre, signal, mirror" technique
x) East european flower sellers standing in the middle of the road.
y) Builders lorries, stuff being chucked on that bounces off into the road, or ropes being thrown over lorries loads and lassoing a passing rider ( i've seen it happen in drury lane to a K100 rider)