We talk about WORK a lot - because we are both in the same field and in the same type of career (tenure track faculty at research universities)
We talk about work in general, in terms of our careers, about what's going on in our departments, politics, etc.
We also talk about work in particular, because we ocasionally work on research projects together. We just recently got a theory paper accepted in a top psychology journal, and we've been working on a manuscript for a different journal (in fact I am proof-reading it right now). We're also planning and coordinating data collection that's starting in the Fall.
When we're teaching, we can bitch endlessly about students
Other than that - we talk about politics, news, philosophy, music, my freakshow family, her freakshow family
, interesting things we've seen - yesterday I almost hit a deer on my bicylce, and today she walked through a music video being filmed in Nashville. etc. I don't anticipate running out of things to talk about.