Undeniably, indisputably number one. Where is the first place you go after, say, 45 days on the International Space Station? Or two months trapped in a mine?
And besides, it's the only thing left standing after the tornado.
2) Gutters and Downspouts
You never think about this lowly pair, do you? But there they are, working hard every day, quietly collecting rain, leaves, and the occasional bird's nest. Keeping your bald spot dry and keeping water out of your basement.
Big Brother snuck this into your house when you weren't looking. Filtering out all the nasty stuff YOU brought in, serving to protect you from yourself. But don't take it for granted, it'll turn on you.
4) A Room You Rarely Go Into
There's a room in my basement that I actually didn't remember was there. Went down there one day and said, "where does this door go?". Opened it and found a lot of stuff that I'd forgotten I had, and had since bought another of. So now I have two Austin Powers bobbleheads.
5) Concrete Blocks
Is there any decorating element more versatile? From bookshelves to speaker stands, nothing says "dorm room" quite as well as this ubiquitous 8" x 8" x 16" design element.
A couple of blocks, a couple of boards, and magic happens!