While most travel nurses are single, my experience has been that there are also a large number of nurses that travel with their husbands. The majority of them that travel around do find some sort of work in the location the nurse is working in.
Some have "portable" jobs like an online or internet business, or a "work-from-home" type job. Others have been able to find short-term positions, that they arrange prior to relocating, that only last for the duration of the contract.
Your spouse could also explore working in the hospital you will be in. The demand for nurses is so great, that they may be willing to employ your spouse just to get you to their facility. Consider speaking to your travel nursing recruiter about negotiating this before you sign to work at any hospital. Many hospitals are glad to accomodate you and, depending on their needs, are happy to gain two new employees rather than one.
It is easy to find work in a majority of the areas you travel in, but if you are looking to relocate to be at travel nurse in a rural community, it may be difficult to find jobs for your spouse. In those types of isolated conditions there aren't usually many job availablilties, but if the pay is good enough to sustain both of you, then your husband could consider being a "house husband," which usually works out great, especially if he's a dad too.
If your husband finds it difficult to find a job that will allow only temporary employment, remember-you can always renew your assignment contract and stay for an extended period and if you end up liking the location, you can always take on a permanent position at the hospital there.