You may already know about this, but I didn't, and it's one heck of a time saver. In CS5, if you're using any brush tool, you can hold down the control/option keys (on a Mac - not sure if it would be control/alt on a PC) and drag your cursor from right to left across the brush circle to change the size and up and down to change the hardness/softness. Dragging it to the right makes it larger, and dragging to the left makes it smaller. Up is softer; down is harder. You can see the change in the top menu. I've taken several webinars lately that have shown that shortcut, and I love it.
My screen doesn't show it, but the instructor got a red circle within the circle that showed the changes as he was making them and the red disappeared when he stopped dragging. I'll have to look into that, but at least you can use the shortcuts. I thought using the brackets was great, but this is even better.