I used to do ~185 mile round trip daily and my list looks similar to frez's.
If I had to do it all over again I'd work to this list again (compiled through experience over 70k+ miles in 3 years):
Must have items:Handguards (currently have Polisport Sharp guards as shown above)
Heated grips
Bar muffs (in the winter)
PD Oiler (I have the normal version, but the Mini is just as good)
Madstad screen bracket
Aprilia Tuono Mirrors
Mirror extenders (that move them more outwards than up)
55 litre Givi Maxia top box
Nice to have items:Mudguard extender
Better headlight bulbs (I use amber Phillips MotoVision bulbs)
Crash bars (just in case)
Fork gaiters
Fork brace (helps a lot in windy conditions, almost a must have)
Gear for yourself and misc items:2 pairs of gloves
two piece waterproof suit (this really helps helps in winter, both with the cold, the wet and to keep your other gear clean and salt free)
something to keep your neck warm without restricting your movement (my textiles have a high collar and in the winter I use 2x buffs too)
Pinlock!
Something to clean your visor with
Something to clean your lights with (don't forget your rear light, leave your number plate as dirty as you can
)
Carry spare keys and alarm fob and such in a hidden jacket pocket
Carry spare ear plugs (in fact, always wear ear plugs, it helps with fatigue, it's dangerous being tired, falling asleep on a bike is terrifying (don't ask...
))
Make sure you have sunglasses/internal sun visor/dark visor that is kept in your top box in the lighter months so that you are never without it
Some way to temporarily plug a tyre and inflate it (search "Tyre Plug Kit" and "Airman pump" on the forums)
Tyre pressure gauge (just a cheapy one will do, as long as it's reliable)
Small can of WD40 for things that should be moving, but aren't (also good to start fires with
)
Mini roll of duct tape and some cable ties for things that are moving, but shouldn't
Superglue to mend that cut finger/hand/etc.
Vynil gloves (Who wants dirty hands in their gloves? Keep them clean if you have to do something at the road side.)
I don't carry spare bulbs, the front and the rear has 2 each already and it's unlikely both will fail at the same time, just check them regularly.