To pack or not to pack?

I am finally taking a serious look at packing today; especially as to what I can and cannot take in my carry-on bag. So far as I understand it, I can take as many 100mL (or smaller) bottles of liquid, gel or aerosol as I can fit into a sealed 1L plastic bag (which is not the large ziploc, but the medium one). I don't think that it will be a problem as we will each have a checked bag that we can put whatever else we might need in. Aside from the liquid restrictions though, I have to figure out what else warrants inclusion in my carry-on: books (of course!) snack foods (can I take a bag of soya nuts?), some toiletries, camera, ipod, and I haven't decided what else yet. Any suggestions from wise travellers?