Most useful cycling accessories

An accessory defined as something that didn't come with the bike, is not essential to forward progress or basic comfort but has been found to be inordinately useful to me as a cyclist. These are in no particular order and I'm still not sure if I've missed something. I'm not including a puncture repair kit and spare inner tubes as I'd consider these essential requirements. Anyway these are 10 of my favourites.

1. Decent framefit pump. Either the Zefal HPX or the Blackburn version.
   
2. Track pump. So easy to ensure tyres are up to pressure. One of the best things I've ever bought.
   
3. Mudguards (and, for the regular winter bike: mudflaps). I don't enjoy dirty clothes or bike. And I think they look right.
   
4. Carradice saddlebags (especially my olive green Barley). OK - I can see you are starting to think 'mudguards AND a Carradice saddlebag! Must have a beard and sandals.' Nope.
   
5. Bagman support for Carradice saddlebags. Keeps it upright so things don't fall out of the side pockets and stops it from chafing the backs of your thighs.
   
6. Cycle computer. I don't have one on all of my bikes but its great to see how far you have gone. Its also depressing to see how slowly you have done it.
   
7. Good lights. No point in skimping on something so essential to safety. However, I'm not in the same league as Ian Loasby when it comes to lighting up half of Sheffield when I'm riding at night.
   
8. Toestraps. Only use toeclips and straps on one bike. All the rest are clipless but they are just so useful for attaching things to racks, saddlebags, panniers, handlebars, frame etc. Don't go anywhere without them. Same goes for cable ties. Always have a few in the saddlebag.
9. Rear rack. Only have one on the touring bike but it makes the bike so versatile.
10. Cycling mitts/gloves. Make a difference on long rides and saves the skin on your palms when you fall.
    

I've tried to differentiate between accessories and developments/ improvements. For example you could say that a clipless pedal system is an accessory based on my definition above but I'd actually class that as an advance in design. I'll get round to listing a few 'best of and worst of' cycling developments soon.