Many of my clients use sticky posts. They are also used, as probably mentioned, by many Themes to add posts to sliders and featured areas of a WordPress Theme, something I've found easier than dealing with a custom category that you have to remember to exclude from Category widgets and other listings and menus.

Sticky posts are also a great way to easily create a hybrid or integrated site model with WordPress, adding a static area to the top of the front page with the posts scrolling underneath.