Well I won't list the FULL contents of my backpack, but I found some handy things were:
1. Morillo-wool socks with coolmesh lining. I payed CDN 12 per pair, but they were worth it.
2. Clothespins. The clothes I brought (very few, for less weight, so i washed them often) were often not dry in the morning from their evening wash, so clothespins were very handy for attaching them to the back of my pack to dry.
3. Colour-correcting sunglasses. Its amazing how good, reasonably bright sunglasses can take a type of stress off the body when you're staring at a bright white-ish road all day.
4. Walking stick. I started in Le Puy in France, and bought a very light wooden walking stick with a metal tip for 7 euros from the front of a produce store on the road from the train station (they're more expensive in the tourist knick-knack shops i think). It served me very well, gave me confidence when confronting threatening dogs, and helped me in the ascents/descents. And when my left foot or knee was aching, I used it to support my left side (by using it with my right hand), and when my right leg or knee was hurting, vice versa. Its like having a friend along almost...plus, I can't be sure, but I suspect i got a more friendly reception from locals because of my wooden stick and big floppy hat...showed i was more of a pilgrim than hiker. Just a suspicion, though.
5. Big, wide-brimmed hat. I hate using sunscreen (b/c of the oily sensation on my skin), so i found if i wore this hat, I'd be fine to not use any on my forehead or around my eyes. But even if you do use sunscrean, its nice to keep your face in shade all day.
6. Compass. This is more handy for the lesser-known routes, say in France, but it was incredibly useful to me from Le Puy to Aumont-Aubrac, in the more hilly areas.
7. And yes, deoderant. I bought a really small deoderant stick (you may want to buy small everything, by the way...drug stores often have traveller-size things) and was very grateful for it...its only a few ounces, and keeps you smelling ok. If you stay where there are showers, and shower every day or second day, and wash your clothes occasionally, you shouldn't smell TOO bad.
Hope these suggestions help. Anybody else have any?