The smell of wet earth after a warm rain....

Seeing all three cats curled up together for the first time after the two kittens were introduced to the house. *gurgle*

Snapping a snapdragon.
A UTI.
Seeing a circular rainbow (from above, projected onto a cloud, with the shadow of your airplane in the middle).
The instant when a snowflake finishes melting into a water droplet.

Watching lightning make a full 360-degree circle in the sky above your head before the rain actually arrives.

The moment of entering a sushi trance: when the sensation of taste overwhelms all the other senses.
Looking down over Seattle from a high place, and falling in love all over again.
The realization that a project, drawing, or painting is done, and it looks just right.
Orgasms. 'nuff said. ;)

Waterfalls
Laughter
Redwoods
My garden

Taking my bra off when I get home after a long day at work :-)