These are mostly based on my own measurements, but a few also come from Healthy Bread in Five Minutes a Day. Some products' weight vary by company, so if in doubt, do double-check. All flours listed are La Milanaise organic flour except where indicated by an asterisk. A good intro to weighing ingredients is here.
Weighing ingredients ensures accuracy (sifting flour is unnecessary) and efficiency (no having to scrape and wash measuring cups with honey, molasses etc.!). You can get a good electronic scale for about $10 at Canadian Tire - what are you waiting for? I write the weight of ingredients called for right into my recipe books next to the volume given - and of course, UK recipes all use weight, so all your bases are covered with a scale!
When cooking, just put your mixing bowl right on the scale, measure in, mix, return to scale, measure in, and so on.
I keep this chart in my pantry cupboard, and I encourage you to print this off for your own use, adding whenever you see fit.
Whole wheat bread flour: 142g/c
White wheat flour: 141g/c
Whole wheat pastry flour: 153g/c
Buckwheat flour: 160g/c
Spelt flour: 147g/c (I didn't note whether this was whole or white, but I think it was white!)
White kamut flour: 154g/c
Whole kamut flour: 137g/c
Sprouted spelt flour*: 130g/c
Quick oats: 93g/c
Wheat bran: 59g/c
Cocoa powder: 80g/c (Camino brand - I think No Name is 110g/c - I have both weights written down on my list but I didn't note which the 110g/c refers to, so I'm going on memory - if using a different brand, measure it once and write the result and brand in your chart.)
Brown sugar: 206g/c packed
Molasses, fancy: 320g/c
Maple syrup grade #2: 333g/c (note that the weight does change depending on grade - I have tried grade #1 as well and there was definitely a difference, but unfortunately I didn't write it down!)
Yogurt: 280g/c (full-fat homemade)
Liquid vegetable oil: 220g/c
Coconut oil: 180g/c
Chicken egg, shell off: 52g/egg (large size)
Duck egg, shell off: 85g/egg
Feel free to submit weights of products not listed here - nut flours, blackstrap molasses, and other brands' weights would all be useful to have, for starters!