After skipping it a few years I’m doing some serious spring cleaning here and combined with a shopping spree of historical proportions a few weeks ago I now have a bag full of non standard power cables etc I can’t use anywhere around here. Just throw them away in their little plastic bags brand new from the factory is against the grain to me? Any better solution I’ve not thought of? 
You can always try to sell them.
These cables are usually relatively expensive to buy as replacement parts, so you might be able to help some people out if you know what they’re for 
If there’s a Craigslist equivalent or such in your part of the world (wow http://stockholm.craigslist.se/), that’s one place you could mention them, the other possibility would be to seek out a second hand shop that deals in electronics, offer them as barter for something cool, or just be charitable, help your fellow man and give them away.
There’s an electronic surplus store in my city (when I am there) that caters to such “junk” and I actually found two obscure power adapters for a camera I had picked up without adapters.
Good karma if nothing else. 
Cut the “wrong” ends off, and replace with connectors you can use. This is the optimal solution because it consumes time and money, yielding a “customized” product.
That’s better than it seems, me thinks. It’s even good enough! 
It even gives me something to do on rainy holidays! 
It’s a plan. Thanks!
Make music, not cables. 
Make both!