This is more or less what I am using:
http://www.thingiverse.com/thing:36813
![Cable_Tie_Belt_tensioner_preview_featured.jpg]( "Cable_Tie_Belt_tensioner_preview_featured.jpg")
My belt isn't continuous, so the yellow cable ties that they used in the picture above are on each end of the belt.
If I ever design my own carriages, it will probably incorporate something like this to pull one end of the belt:
http://www.thingiverse.com/thing:26361
http://www.thingiverse.com/thing:164339
http://www.thingiverse.com/thing:36813
My belt isn't continuous, so the yellow cable ties that they used in the picture above are on each end of the belt.
If I ever design my own carriages, it will probably incorporate something like this to pull one end of the belt:
http://www.thingiverse.com/thing:26361
http://www.thingiverse.com/thing:164339