I can't seem to find one that works for most of her recipes either, so I will check out your link Mariannes. Thanks for posting!
rawmamanibbles: In lieu of a proper conversion chart, I have just been experimenting with measurements that best that I can. I don't know how long you have had the book, but I have had mine for about a year, and I have found her recipes to be pretty forgiving when it comes to amounts. BTW, how do you like the book? I love her recipes and so do my kids!
I've found Google the most useful tool so far, especially when using Firefox, in which case you can just enter something in the bar at the top right, like '12 kg in pounds'. Another useful tool is Wolfram|Alpha: www.wolframalpha.com . Just enter '3 pounds' and it'll convert it to a bunch of other units, as well as give an indication of how much it is (e.g. 4 soda cans). And as a nice bonus, you can enter 'apple' and get nutrient information.