Guy has a whole bunch of glass tubes for sale.
Can be used for almost any kind of application that could use solar generated heat. He swears it is child's play to get one of them up to over 250 degrees F. And he tells you how.
Anything from some kind of icyball affair to electricity to hot water--"domestic" or radiant heat.
(although one of the nice things about the original icyball was how really sturdy it was.)
http://www.fossilfreedom.com/products.html