Okay...let's see:
*A Littman if she doesn't already have one
*Does she like jewelry? If yes, do you trust yourself to know her style? If yes, why not memorialize the occasion w/ a really neat ring that also has an engraving on the inside...something do w/ her new journey as a nurse? A ring w/ her husband's fingerprints imprinted on the outside (have you seen those?) since he is away a lot.
*A guided meditation CD to help her relax at the end of the day (love these!)
*A small diamond pendant? Or a pearl maybe?
*A gift certificate to her favvvvvorite clothing store so she can go have a girl's day
*A gift cert. to her and hubby's favorite dinner place, and then you babysit so they can have a romantic night out...maybe tie the cert. to a bottle of chilled champagne
Well...that's all I got for now...