The temperature outside.
Have the current temperature right on your toolbar. You can choose from a variety of units to display it in and cycle through them by clicking the icon. The units and formulas are fully editable in the options, along with the icon color and polling rate.
• 2.1.0 - add more options
• 2.0.0 - major update
• query.yahooapis.com - to retrieve the forecast
• Location - to know what weather to show