And some non-material tips

Improvisation. Take only the things that you need indispensably. Imagine an average day of cycling and go mentally through the daily procedures and the things needed. Don't concentrate on too many accidental events. If they happen - and these are low probability events by definition - count on improvisation and help or paid service from the local people.

Rain. Rain is a special subject which I will research in deeper detail in the years that will follow. So, unfortunately, I can't give you much useful advice now. Come back here in about a year's time and you'll hear the words of an old wise man. For now, based especially on my last trip through rainy North America, I only know that nothing that I tried so far, works well. I tried all sorts of jackets, pants, breathables and unbreathables, overshoes, even tyvec suit for nuclear power-plant workers, and I still haven't find the solution. Well, maybe one - and a very lightweight indeed: just grin and bear it. If I am doomed to be wet I might as well do it with less/lighter gear. Who knows, maybe the best way is to ride naked through the rain, having your dry clothes ready tucked away in your bag.
Update. Well, I am a few years older now, and maybe a bit more experienced. I'm still in a pursuit for the magic rain-formula, but meanwhile I've come up with few minor solutions. First, you'll have to realize that - no matter what you wear or don't wear - you will be wet when riding in the rain. Once you come to terms with that, world will be much nicer. Starting from the head: cycling cap is a perfect headwear (in rain or sun): protects from the rain, restricts the heat loss from the head, brim stops the spray. I now prefer a light water repelling (or "resistant") top instead of full rainproof jacket, because it's lighter, packs smaller, can be used in wider range of circumstances (cold mornings, wind, descent) and has less condensation. Idealy it would come with armpit mesh for ventilation. Under that I wear a cycling top (a jersey) and thermal arm warmers. Plastic gloves (the kind you get in petrol stations or in fruit-departments in supermarkets) are surprisingly useful in rain - just slide them over your cycling gloves. Too bad they don't make XXL versions. Even better are gloves made from a plastic cover of a magazine: see instructions here. I prefer not to wear any kind of rain protection for the legs. Feet: wrap them in cling foil. A hint about the cling foil: cut it in half so that it has the width of a bandage, that way it's much more practical. To reduce the spray to your back side (unless you have a mudguard) you can make a "tail" out of a plastic bag and hang it from your waist. All this is sufficient for more or less mild rain conditions. If the temperature is low or the ride is long, keeping dry may be the only reasonable solution - that might mean to stop cycling.

Toiletries & medicines, 2009, Canada.

Washing. In everyday, non-cycling life I don't use much toiletries; water, soap and tooth paste do it for me. So it's easy for me to give up on them on a cycling tour. Beside that I like to cycle alone and I am free of any social restraints, including body odor. If people don't like the way you smell, whose problem is it anyway: yours or theirs? I do like to shower or wash at the end of the ride, but if there is no such possibility, it's no disaster: I know the sweat will dry out in an hour, leaving the dry, crisp layer of salt that I lick off and replenish the electrolytes that were lost. I used to carry liquid detergent and tooth paste in film boxes taped to the bicycle, but stopped doing so after I realized the pure water is enough to make me feel fresh and clean (even for shaving and brushing teeth). Sooner or later I come upon a camp or a hotel where they have some stronger chemical stuff for more radical treatment. I don't know what is my days-without-shower record, but it's certainly nothing special compared to some "self-sufficient" stories.
On the other hand, it pays off to wash your stuff. The dirt, sweat and dust collect in the tissue and make clothing up to 10% heavier. Or even more. My old bubble wrap sleeping pad (which I never washed) is almost twice heavier than the new pad of the same dimension (135g vs 72g). Of course, the same applies when you wash yourself. I'm still not sure why I feel good after a wash: because I am clean or because I am lighter?
The picture shows my toiletries+medical+sawing kit: thread with a needle, razor blades, a roll of white medical tape (wrapped around a piece of cork), a couple of aspirins wrapped in a piece of plaster (plaster not being necessay if you have the white medical tape), 3 vitamin pils (not necessary), two shaving razors and a tooth brush.

Cutting. Cut, cut, cut. The things produced nowadays - apart from those made for TdF racers - are redundantly designed. Cut your shirts, tear off buttons, straps, collars and not needed pockets. You will save few 100 grams, you will learn how the things work and will develope an eye for ridiculously redundant equipment. If you are creative enough, you may start making your own stuff. It is well known truth that the only equipment that fulfills all your requirements is the one you make - or at least modify - yourself.

Number of things. An equally important point to weight/volume is a number of things. The more things you have, the more time it takes to pack them and to find them - and there is more probability you'll loose them. The ideal would be not to take some things at all - I got rid of stoves and books in this way. There is a deffinite beauty and elegance in traveling in minimalistic style. Alternatively, use the same thing for multiple purposes as much as possible. Bubble wrap used as a sleeping pad as well as for water-proofing or cue sheet used also as a scrapping spade are good examples, but I can't really give you much more advice here - obviously this is a promising field that needs much more research.

Adding up. Little weight and volume savings add up. For example: on the australian tour I had the smallest and lightest pack so far, below 6000 grams, even though I had a helmet (280 g) which I usualy don't wear. About 700 grams lighter pack compared to the one on Indian trip came from little changes: lighter rain jacket, ommision of batery charger, lighter lock, only one spare tube, razor blade instead of a knife, cutting the pedal wrench in half, shorter socks, ommision of tooth paste, smaller medical & sewing kit, cutting the handles of a razor and toot bruch, less pages in a notebook, etc. Some modifications to the bike were made too: I cut part of the seatpost and removed the kick stand.

Mountains. Do you like riding in mountains? Have you wondered why is riding in mountains much slower then on flat ground? Well, it must be connected to weight somehow. See the miscellaneous bicycle wisdom page for an explanation.

Monitoring. Once on the road, monitor the frequency of the use of various objects. The ones you use infrequently are the candidates for omission on the next trip.

Circulus viciosus. Reducing the load and volume is an iterrative process that follows the "lightening circle". Always think of the mystical circle of light weight touring: less weight -> less volume -> less containers -> less weight -> less mechanical problems -> less spare parts and tools -> less weight -> ...

The ultralight Zen. At the end let me address the usual, fully loaded way of touring. My intention is not to convert anyone to either light- or loaded- or any other way of touring. This site is ment to provide some ideas for those who are willing to sacrifice some comfort for a lighter pack. There seems to be an oppinion that by doing so one sacrifies also one's 'freedom', 'independence' or 'self-sufficiency'. I don't share this view - let me end with a bit of Zen-touch: the true freedom is in having less.