nothing affordable that works (that I know of).....Gefen has some that may work but they are pretty expensive from what I have seen.
Unless this is some sort of commercial solution for multiple monitors with pre existing coax runs, this product will be way too expensive.http://www.gefen.com/kvm/dproduct.jsp?prod_id=5303
Note: Reading about that product it seems to have been discontinued and superseded by this product http://www.gefen.com/kvm/dproduct.jsp?prod_id=4318
which is wireless and way to expensive for me.
use google and the term "coax to hdmi" for other options or maybe someone else here will have some input.....