So if you havent done your Christmas list then a decent bumbag could be something to consider.
Here is a brief list of what I ALWAYS carry on the trail or on Rallies.
The bag is an OGIO one and was from Husqvarna for about £40. It has 2 side pockets (one with waterproof bag liner) one front pocket and a main compartment with spanner loops and zipable net pocket. The zips need a bit of WD40/TLC from time to time, as they clog with mud but other than that its a fairly sturdy bag that carries quite a lot. I wouldn't expect it to last 2 years if it gets a lot of use but if its occasional trail riding you do, it should last years and years.
I don't carry tools or spares for others, so all the tools listed are for my bike but they would fit any other KTM or Husqvarna.
Spares carried:
2x 100ml shot bottles of 2/ oil (enough for 10 litres or about 75 miles)
2 x ring split links for my chain. and a couple of links. (usually there is also another one for an Oring chain as well)
A new bagged and oiled air filter. (kept in the waterproof side pocket of the bumbag)
New or known good Spark Plug,
New throttle cable,
New fuel pipe,
A selection of nuts, bolts and screws, a few pieces of wire and some insulation tape, (including brake pad pins and lever pivot bolts)
A selection of cable ties (various lengths and sizes)
10-15metres of Para Cord. (Although thin this stuff has a huge braking strain so can be used for towing)
Spare circlip to hold the front sprocket on,
Neoprene gloves.
Few bits of rag,
Spare Brake and clutch lever and caliper/brake pad pins (you stand a chance of finding your pads when they fall out but not the pins!)
Tools carried:
Standard Husky/KTM tool roll (includes most of what you'll need)
Selection of stumpy combination spanners to undo all nuts and bolts (with the only exception of the swing arm)
Chain splitter
Pliers and circlip pliers
Selection of Allen Keys for all Allen bolts on the bike (including the small one that hold the carb top on!)
Small screwdriver and screw driver bits
Small mole grips. (handy when used with a m6 nut to push a split link plate on)
Open ended and cut down spanner for the spark Plug. (drilled to lighten it)
I don't carry tyre levers, spare tubes, pump, puncture repair kit or anything for the wheels as I use mousses. (the only guaranteed way NEVER to get a flat tyre, A debate on legality of mousses and or the advantages of TUBLISS is not necessary here! its been covered elsewhere and is a matter of preference)
Whenever I work on the bike at home I always use these tools from the bum bag. that way I:
1) know I'm carrying the right tools needed,
2) I know I haven't lost anything.
3) Familiarity means you always know where things are and don't have to open unnecessary pockets to find what you want.
In my rucksack I would also usually have my waterproofs. My camelback, a spare pair of gloves and some winter road gloves if its that time of year. something to eat, a waterproof dry bag with phone, smokes, lighter and house keys etc. (if it was to fall out I shouldn't have any trouble finding it as its bright orange!)
I may also carry a selection of maps and a spare battery for my Garmin and camera.
As is say, this is what I carry. I always work on the principle of carry everything and then hopefully you'll never need any of it.