I just bought a new TV for the den after the old one went out. I created a folder in my Documents on my computer for User Manuals, then created one for the new TV. I went to the company website and downloaded the user manual for the TV I had purchased, the tech sheets, scanned the invoice, made a document that included the Model #, Serial #, Date of Purchase, Place of Purchase and saved all this to the new TV folder. While on the company website, I registered my purchase and then tossed the hard copy.
I am now checking other manufacturer websites for the user manuals to things I own. If they do not have one to download, as I come across them while organizing drawers, I scan them and save them to my documents folder on my computer.
If I needed to find one, I'd have to look all over the house for it but with it on my computer, piece of cake. I'm not worried about losing the info in a computer crash either since I subscribe to an online backup service which has already saved my behind once. My hard drive crashed and I didn't lose any of my files or photos.