While I think not bringing a map is foolish, I can see Xeroxing the pertinent areas or cutting down the size of your map. I Xerox the pages of the guidebook that I care about, and leave the rest at home or in the car. I wouldn't go anywhere without water, but you can shave a little weight by reusing a 20 oz. plastic soda/water bottle from the cold case of the convenience store instead of bringing a giant Lexan Nalgene. Personally, I prefer the robustness of the Lexan.

Some of the ultralight crowd do go overboard -- by the time you're sawing the handle off of your toothbrush (as I've seen recommended), you need to reevaluate what shedding an additional gram or two is really going to accomplish.