I get annoyed by anyone riding too close behind, especially in traffic. I also hate riding too close to behind another cyclist as my visibilty and the available time to react are almost zero. There is another rider who does a similar commute to me, and he will happily let me take the lead for the whole of our shared journey. Another sleepy biker ran into me once because he was too close and not paying attention. On another occasion I went to overtake a slower rider, and they decided (without looking for traffic or a hand signal) that it was time to turn right. I hit the rear wheel of the bike, went straight over and landed on the tarmac on my bum. Luckily there was no damage to the rider bikes.
On the other hand, I'm not always the sinned against party... I tried to out-run a bus this morning on one of my least favourite roundabouts. It was OK, but I do feel daft and I deserved to be honked for being a moron
.