Breakfast Topic: Best macros

Macros are a useful way to create custom commands, from witty sayings to more complex spell invocations. Many of the addons available obviate the need for macros by providing a lot of automated speech and the like, but there is still the occasional need for a quick and dirty macro.

What macros do you use? Which are your favourites?

Personally, I started out experimenting with macros when I was a very young Druid, with a /say macro that would tell targets of fly-by buffings who was responsible. I came to my senses quickly -- it was a remarkably spammy macro and I cringe when I see it still in my macro list. I've also used the macro functionality to change spell icons, as some of my different characters share the same icon for separate actions, a confusing situation. However, I've never found a 'killer' macro, though I'm happy to be converted.