Playing with a kitten.
Coming to the counter of a library or bookstore with an armload of books, knowing you will have an interesting week of reading ahead of you.
The smell and sound of a pot of coffee being made
The ritualistic ceremony, the automatic motor movements, involved in the act of making a pot of coffee or a kettle of tea. Every sincere coffee drinker has a ritual which can rival that of Lu Yu.
Making a reference such as the above, hoping that someone will get it.
Noticing the hamster in Terry Gilliam's movies.
Coming home to find your cats perched on the windowsill, watching you as you walk to the door.
Being in a densely urbanized area where, at night, the sky is a hazy orange color and the stars are invisible.
Being in a rural area where the sound of crickets and frogs blends with the sight of the Milky Way.
That moment where a seemingly difficult programming problem suddenly vanishes.
Looking at a difficult section of code and knowing how much fun one will have in figuring out exactly how it works.
The potential of an empty emacs buffer.
Using a tiling windows manager, without a mouse hooked up, and a Dvorak keyboard, and watching people go insane trying to "just look up something" on your computer.
Finally playing a difficult piece of music as it should sound.
Seeing a testbench pass after hours of debugging.
Seeing a testbench pass on the first time.
Experiencing consilience.
Teaching a child a subversive fact which he will be able to intimidate others with (why the sky is blue, what handshakes come from, that the red in many kinds of makeup and artificially processed food comes from ground-up beetles)
Actually managing to pay a bill on time.
Realizing you can't remember the last time your debit card was rejected for insufficient funds.
A first kiss after a long period of doubting one's chances of connecting with someone else.
Laughing while having sex due to a cat pouncing us, or suddenly noticing that the next door neighbors are watching loud porn.
Meeting a woman who likes it when you make fart noises on her belly.
The feeling of putting on glasses for the first time and suddenly seeing things as they should be seen.