There are so many, but I would have to say Velcro. A fantastic product with so many uses. Of course a closer devices for quick opening, it's versatility to be used on so many surfaces makes it a staple in everyone's sewing kit or junk drawer. The sound, the sound known all around the world as you tear the two pieces apart.
Kitchen paper. I don't know how I ever managed without it. I use it for just about everything. I never buy cheap ones - I go for thirst pockets, or those that you can use when wet, because they can do such a lot of different jobs around the house. If I was really destitute, I'd cut back on everything else before I stopped buying kitchen paper.
Watch. We can't live without time. What would we do? Use a stick in the ground or a sundial? Another great invention: the sofa. Ah, how nice it is to just sit on a comfy soda, drink a coffee and read a book!
I will say the best thing to ever be invented is a tool that helps people to make unusual bracelets. I have an invention but haven't sent the money in to get it to the market yet. I plan on doing this in the next few weeks so it will come into the market in 2013, for everyone to use, especially the ones with arthritis hands.
So far, two of five items mentioned have been electronic (or usually powered by electricity). I think the best invention that fits would probably be the pen. It's old, but it's incredibly useful.
I would say that eyeglasses is a great invention. I already have blurry eyes ever since I was a teenager, so I couldn't imagine going out of the house not wearing my eyeglasses. Without them, everything would be blurry.