Well..... We won't discuss the number of them holding things together in my car....
Other ideas:
-If you have something that HAD a bolt and nut set holding it together, a zip tie often can make do in a pinch.
-Used them to replace the cotter pins in my old external frame pack.
-Use them to make belt loops on ALICE-pattern pouches, and attach pouches of all types to packs.
-used them to field expident a flash light holder to hard hats several times, everything from solitaires to surefires and scorpions.
-to replace a sling clip that snapped from cold on my old LLBean dispatch bag, and to replace a couple of zupper pulls.
THe extreme for me was using them as part of a splint, outisde the padding.
They are somewhat redundent. If you have fishline/dental floss, some wire and a bit of duct tape, those cover a lot of what you can do with zip ties. Until you have to try to use duct tape on something that is below freezing or oily and won't stick. Or trying to tie a knot when it is 40 below out, and any skin that touches anything is probably stuck there until spring. Or you don't want to have to worry about the stabby-bits from wire, or need it to be non-conductive.
A zip tie doesn't care about cold (that much or wet, and it can be put in one handed in a hurry. It is part of the bag o' tricks. After all, the two blades in the leatherman, the one in the micra, the pocket knife and the razor blades in the PSK can all be used to cut.
Although, I'm a professional computer and electronics geek. I carry a half dozen blaze orange and black ones tucked into the pouch with my leatherman and minimag, along with a bit of wire and a p38, and more in my pack. I use them more than I do duct tape. :P So I might be biased.