I've seen it only once. Sorry, no pictures though. I've also only seen one of my geckos lick the calcium dish once. I was like, "wth, they actually do lick that stuff up". =)
I've seen Yoshi drink on numerous occasions. It's kind of funny to watch. Unfortunately, she only drinks at night, and my camera doesn't take good pictures in red light.
"mom should refill the water dish...lazy mom."
I've seen both mine drink from the water dish and lick the calcium dish, but it's rare. They probably do it in the middle of the night when no one's around. Perhaps it's a very private thing to a gecko - like using the bathroom for humans or something. lol