The coolest way to adjust text properties is to scrub the little icons to the left of the property fields. For instance, you can adjust font size by clicking the icon that looks like a T with a cast shadow. Don't release the mouse after clicking. Instead, hold down the mouse button and drag to the left or the right, as if you're trying to drag the icon off the Character Palette. Dragging to the left will interactively decrease the font size ; dragging to the right will increase it.
This feature is so cool, Adobe has also added it to Photoshop CS and Illustrator CS.