Actually, the Internet. I still think it’s amazing that you can post something to a board and sell something on E-bay and communicate around the world. I do genealogy and still get excited that I get e-mail from possible family members from France and Russia or only thirty miles away. Otherwise, I would have never known they existed.
My kid - he’s a interesting person. Even other people say so. He’s pretty articulate and when he’s interested in a subject, he’ll get memorize every bit of info he can get his hands on until he exhausts all of his resources.
I’m going to go out on a limb and say the US Postal Service amazes me. I know some of you constantly gripe about the price of a stamp or your letter that was 2 days late, but think about how small that letter is, how it gets mixed with millions of other letters on that journey and still usually gets all the way across the US in less than a week. Think of how many thousands to hundreds of thousands of pieces of mail you’ve ever gotten in your life and the comparatively small percentage of those items that’ve gotten lost or damaged somehow, and the fact that most of the work on either end is done by actual humans rather than machines and you have a shockingly low rate of error.
Palm Pilots/Visors/etc amaze me. The first time I saw that commercial where the girl beams her phone number to the guy on the other train I almost fainted. That’s total “space-age” science fiction type stuff, and we can now buy it for around $100.
And of course computers and the internet in general. I love being able to chat with handfuls of people from all over the world in actual time. The simplicity of use also amazes me, especially considering how primitive by comparison computers were just 20 years ago. (I remember in grade school learning basic programming on an Apple IIe: “Line10:print:I am the coolest, Line20:goto10” LAME!) Now I’m able with only the smallest amount of actual knowledge to not only make my own webpage but actually run a business through it. When I was in graphic design school less than 10 years ago, everything had to be painstakingly created by hand by ordering clipart or stock photography from a book, then using Letraset rubdown letters and films etc. Now you can whip up something nearly identical (and often-times better!) in MS Word in a matter of minutes. You can buy your groceries over the internet, movie tickets, book plane tickets/hotel rooms/rental cars, print postage if you have the software (awesome!) see the weather forecast for durn near anyplace in the world at any given time, get info on nearly any subject under the sun. SpoilerVirgin and I were just yesterday talking about all the once-necessary research books we never even pick up anymore because all the info is available much quicker and often much more current online. The way computers have changed banking just in my lifetime is astounding as well. Anyone remember having to rush to the bank with mom so she could cash a check, and maybe even pay the bills by a certain time? Used to be if you missed the few hours the bank was open, you didn’t have any money for the weekend! Now you can pay your bills online, use an ATM or use a debit card to buy something and get cash back just for asking.
And on a lesser note, while they don’t “amaze” me, I find the bar code scanners used at checkouts pretty brilliant. Think how much that simplifies commerce in general. Faster to check out (remember how everything used to be keyed in by hand? And if the price tag had fallen off at some point, too bad for you!) and easier for the shopkeeper, etc to keep track of inventory. Sale prices already programmed in so the cashiers don’t have to remember what’s on sale every week. Quite, quite clever.
Flower petals.
Little children playing.
The texture of almost any surface, textures are so much fun. 
Rain. I LOVE the rain, I perfer to walk home when it is raining rather then catch a ride.
The smell of a new book.
The smell of an old book.
Well, not really an everyday thing for me…
But I think Superconductors are COOL!