I'd say: Bokeh and flat borders (w/o filling) work well. But you should restrict the use to headers and featured elements.
Update (sorry, I was in a rush and forgot to paste the rest of the answer):
As an example, we can take the following header:
Despite of the strong bokeh, the thin lines of the logo + the hr are not too aggressive and fit well. A filling would not work the good (it would cover too much of the photo).
Another example: