If you search http://www.guijaboard.com for "free icons" you will find a post for 1000's of free icons. There are links to free icons allover the internet. You will most likely have to spend an hour or two finding what you need.

Alternatively you can buy the icon set at guifx.

I am test driving a new imac so i dont have access to my graphic software to post an example. I usually have Volume down Mute Volume Up horizontally with the room name above them. You can fit a few rooms per page.

Edit... This is the link to the post with links to thousands of free high quality icons. I posted with my iphone earlier. To lazy to copy paste it then :)

[Link: guijaboard.com]