One thing I love about Android is the ability to quickly set up shortcuts to menus in your Settings or simply having a widget that you can toggle to change things. Quick Settings bests both of these methods by having nearly everything you might want to change on your phone just a notification bar icon away (its the gear looking one). 3G, WiFi and GPS are the things I most often change on my phone, so it is great to have quick access to them. You can either toggle them on or off with the button on the right, or jump into each's menu by tapping on its name to the left.
The other really useful feature is easy access to the various sound levels on the phone. Android doesn't use a one-sound-level-fits-all system, so if I want to turn down my alarm volume (or any other volume), Quick Settings gets the job done elegantly and quickly. You can even toggle between silent or vibrate settings. In addition, it shows free RAM and memory from your microSD card. It is available now for free on the Market. Click past the jump for another screen shot and the usual download links. Thanks to JP for the tip!