Dang it! Wish I had thought of it first Contest

My friend T wanted to invent a self-cooling bed-pillow, but lost momentum after discovering that someone else had already filed the patent. 

There should be a heavy-duty Germanic term for the wish that one had thought of some wonderful idea first...in the way that Schadenfreude means "taking satisfaction or enjoyment in the misfortune of another person" or how Fahrvergnügen means "joy in driving."  Maybe something about being late to the party?

Hmm. Thanks to the magic of translate Google I'm going to just go ahead and coin this one: Rückwirkendneid. (Oooh, as a special bonus, they threw in an umlaut!) That would be Google-German for "retroactive envy." Close enough for my purposes, espcially with that extra-Teutonic umlaut.

What things beget Rückwirkendneid in the husk of my heart? 

Oh, let's see. There's a short list of novels I wish I had written (Elizabeth Knox's Mortal Fire, Jasper Fford's The Eyre Affair, and Kate Atkinson's Life after Life).  And inventions -- like my pal K, I wish I had been the one to figure out that sun-protection neck gaiters were going to be a thing. Also, I wish I had invented Tervis Tumblers because they make people so happy. And also, this website devoted to a collection of cool musical covers also kind of does it to me too. 

Tell me what gives you Rückwirkendneid (comment below) and I will send the top three responses  (or perhaps the first three! or maybe the three regular contributors who have commented on past posts!) a super-neato prize. Or anyway a "prize." Past winners have received things like paperback novels, handmade soaps, and lunch at my favorite Chinese place.