Seal It: It's a deal, it's a steal!
Seal It is a free social application for iOS, described by its developer, Sofa King Interactive, as "the Official App of 'I Told You So' Moments". The interface is classy, with the appearance of a leather-covered notebook, and is very easy to use.
So how do you use this app? For example, you are ready to bet with your annoying little brother on the battle of Wherever having taken place in 1xxx. Rather than dashing to Google it, take 2 minutes to enter the bet and its rewards in Seal it. Thus, when Wikipedia vindicates you, you will actually have proof that "You Told Him So", but also that he promised to do the dishes for the next fortnight. It also work for any challenge you might want to set to yourself (walk 30 minutes every day, feed the cat, pick up the kids at school, etc.)
So, at heart, it works if you're a trivia-addict, a competitive chap, or some who needs a « carrot » to do things. I sure am and I can tell that, had it existed 20 years ago (yes, I'm old), I would have used it extensively at family dinners. As it is now, I love whipping it out, especially during Scrabble games, when someone starts contesting a word I'm sure of... And you end up with a nice memento of your "I Told You So" moments as well as your occasional defeat, but hey, trivia IS your thing right?
And if you need more eyes on you to compel a good behavior or to show off your knowledge of small-sized dinosaurs from the jungles of Chult, you can post every deal and its issue on your Facebook wall, "hire" a witness from your list of friends, or even offer to be a witness for someone else. As I said, this is a social app for friendly bets, school contests, and siblings rivalries.
You can also see it as a way to gamify your life, by setting "quests" for yourself with XP points. You can start right away, thanks to Seal It. You may ask: what’s the difference with just posting on Facebook, Twitter or Google+ your challenge of eating 5 veggies a day? Well, a wall can quickly be bogged down with a lot of other stuff, but Seal It keeps is compartmentalized and easy to access; furthermore, you actually seal the deal with one person, so she too can check pending deal and nag you until it is actually validated as a success as can any witness you invite; last but not least, you keep track of what you've accomplished in, again, an easy-to-access form. There is no better motivator than seeing what you've already achieved.