I have a bottle of LongLife slippery stuff, an 'ikkle bottle of screenwash, both in the side pocket.
A warning triangle clipped in the space on the left. A little blanket in the parcel shelf netting. A Hi-Vis waistcoat in the drivers seat map pocket (told to keep it there by a HATO - if you stop on the side of the road, you can slip it on before getting out of the car).
In the spare wheel well, I have a couple of emergency raincapes, some latex gloves, a couple of black bin liners (handy to sit on).
In the boot, in an old ice cream tub - spare spark plugs, spare bulbs, spare fuses, some garnet paper (don't ask!), some spare tyre valve caps, and a tyre valve core. I also have a pair of overalls (thought for the day - WTF are they called a "pair"

).
If I'm off on one of my long touring hols (usually a month at a time), then I also take 5lts of oil, 5lts of screenwash, some brake fluid, WD40, a tyre compressor (well, that IS my spare in my RS4, along with a bottle of gloop!), a first aid kit, and a second warning triangle (in Spain, two triangles are now compulsory!).
I think that's all, folks!