I have tons of them, and I do keep a ever evolving list of ideas, usually just screwy titles or concepts I'd like to build collages around. I'm not sharing them though, sorry - might need those yet, haha.
A universal human language like Toki Pona
A computer language like Perl or Basic
A comic film like Life of Brian
Could be… The Ipod shuffle, pen tablets and this chair: http://choibyunghoon.com/gallery2/01106.html
Invented the, "Furminator." The ultimate dog fur eliminating device.
Entenmann's Chocolate Frosted Donuts.
Making the movie, "Saving Private Ryan."
Almost anything by Turner, van Gogh, Monet, Pollock, Henry Moore, Jean Arp.
Dada, Impressionism and hieroglyphics
The computer, the TV, and the cellphone.
A world of blueberries (I got this idea after I went blueberry picking), a picture to illustrate what I felt after I lost a dear friend, and one other thing which I cannot mention...
Silver clay for kiln working, glass fusing, and liposuction...lol.
The making of the first kiln, flight and the first computer art program.
'Depression and Ideal' by Carlos Schwabe, the concept of visual kei, and any outfit by Yukari Ohba!
music sculptures written word
Some things I do not remember now, but has surely wondered: Why didn´t I had this idea?
The shoe-glove things that Vibram now makes (I had a prototype of the same thing in 1994, and didn't patent the idea... :-( )
The internet, but Al Gore beat me to it.