Ofcourse, there are alot of Responsive themes available, couple of them for free and also there are paid one's , please check the C5 Marketplace.

Here's the full list- http://www.concrete5.org/marketplace/themes/-/view/?submit_search=1...

thanks for the swift reply - I am looking at them now.

I have a couple very affordable themes that do exactly what you're looking for!

The first is called 'FlexCRETE', which is a light CSS-only adaptive / responsive framework theme with LOTS of page types and customization options:

http://www.concrete5.org/marketplace/themes/flexcrete/...

The second is called 'Foundation', which is similar to the above, but has more user-interface options.

http://www.concrete5.org/marketplace/themes/foundation/...

If you go to either of the above, you'll see a special offer I have where you can get BOTH for one price!