There are a couple of things off the top of my head that I could say I'm thankful to have been invented. Not the kind of thing wherein Twilight fanatics would gush, "thank God for Edward Cullen."
First off, the Internet. Oh yes, the world wide web. Everything seems to be at hand if you've got internet connection. From the days you spend hours trying to connect through dial-ups, to easy-breezy wifi connections, I still am grateful that some brainy people got to create the cyberworld. Without it, my mom would still tell me to browse through that unabridged Webster's dictionary whenever I don't know a word; or the yellow pages when you need to call some place: or wait through snail mail to get in correspondence with someone miles away; and of course the need to have a complete set of encyclopedias that always get outdated after sometime. Luckily enough for my generation, I could simply Google everything and even get translations online, find restaurants nearby and so on and so forth. Through the web, you get a gigantic amount of information, opinions and inputs. Say for example if a new phone comes out, and you're thinking about getting one, you'd have the liberty to Google it to know the specs, read about user's opinions, etc. Whereas decades ago, if you didn't know anyone using it yet, then you'd only have to trust the salesperson who's of course just trying to sales talk you into getting one!
Next up: dental braces. Who could have predicted that teeth could be rearranged? For people who didn't have dental alignment problems, they'd probably not appreciate the existence of dental braces fully. But for someone like me who went from bite 3 (lower teeth in front of upper teeth) to the normal bite 1, a lot has changed. It gave me a boost in confidence, not to mention that it also got rid of my lisp. If they had invented it centuries ago, then probably Mona Lisa isn't smiling without teeth showing, coz she wouldn't have that crooked teeth that she's trying to hide, according to dental experts. :)