For heating water, I almost use exclusively 16 oz. (holds about ~17 oz.) aluminum beer bottles, 0.927 oz., with a Zelph BudLyte stove. Dual purpose heating vessel and water bottle! (Triple purpose if you carry an unopened one to camp...). I recently found an Arizona brand coconut water bottle of the same ilk; the advantage is the shrink-wrap label peels off completely, eliminating the odd stares (and stares of longing) when someone sees me walking around with a beer bottle in my pack.
For water scoops and such, I like cutting down (square, cardboard) quart milk containers (at a slight angle to create a spout). They weigh about 0.8 oz., and most importantly, fold flat like a paper grocery store bag. At the end the trip, I just recycle them.
For water bottles, I prefer the old-style Snapples over the new style and Gatorade bottles as they have a smooth interior without any ridges to trap yucky stuff. I did replace the caps with orange Gatorade caps, however.
I redid my carbon filter using a 20 oz. soda bottle that has perfectly straight sides; I cut the bottom off, inverted it, and pushed it down inside to hold the carbon in place (of course, I punched small holes in it first...).
Normally, I use a long-handled spoon for eating, but I really like the "green spoons" from my local frozen yogurt place. Not a long handle, but they pack and work well. I'll have to guess the weight at 0.3 oz or so.
Old contact lens cases are great for holding stuff from tubes: neosporin, medication, maybe sunblock, etc. The free ones from solution packages are thinner and lighter; just make sure you use the ones with screw caps.