Whoever does need it, I give you permission to throw out all your old cables, power adapters, and routers. Yes, on the off chance you do decide you need a Palm III dock, Linksys WRT54G, or Sony PSP charger that means you'd have to buy one on Ebay, but you can cross that $10 bridge if it actually happens.
For me it's not the cost that bugs me when I don't have a part, but rather the disruption to my flow. If I can't get a project done all at once I'm much less likely to ever get it done.
For me, the hardest part is actually figuring out what the cable is called in order to find a replacement.
And whoever needs something else, I give you permission to ignore this fool and keep your box(es) of cables. I don't regret a single thing about my ~8 boxes of cables.
Throwing away proprietary cables is a sin. Throwing away standard commodity USB cables is not so much
No, this method does not work. I tried, got rid of all those stuff because why would I need it ever again. And of course a month later I needed that one stupid thing right there and then. And I remember throwing away... Not again, I keep at least one cable of each in a separate box to find immediately, the rest is stored, it is not asking for any money.