Heh, I do the exact same thing. Especially with Ikea furniture - I would tape the wrenches, manuals, etc somewhere not easily noticeable.
Another thing I do is behind my TV, or in the back of my computer, I create little paper tags that I tape onto the power cables. So, in case I need to unplug something from the wall, I don't need to trace the connection to know if I'm going to unplug the TV and lose all my presets, or just the floor lamp.
I do the same for "accessories" - for e.g if I buy a desk and assemble it - I then take a zip-lock bag, put in the wrenches, extra screws, fasteners, what-have-you, and tape it to the desk where you can't see it (usually on the back, or bottom if possible).
I do this for almost everything I own - I even tape the instruction manuals to the back of appliances.
This way, I don't have random items floating around the apartment, and I know if I need to fix, replace, or dissemble anything, I know I don't have to hunt around.
I guess this is an extension of jgrahamc's idea - take pictures as you assemble, fix, dismantle stuff, and put them in the zip-lock bag. Saved me endless head-scratching in the past.