Nontraditional summer employment for academics
Have you thought about NASA?

I personally know a fair number of faculty who have spent summers working at Langley and Kennedy, and I can pull up a quick application form for JPL's summer faculty research program. A lot of people, faculty and researchers included, put NASA on a very high pedestal, but it is definitely an attainable position. I am not very knowledgeable of the limitations placed upon you, but I do know fairly valuable work is done, perhaps even outside of your comfort zone -- I know of a fluid dynamicist who worked at skunkworks in Kennedy, for one.