I've been monitoring an online class presented through RWA Pro by Jennifer Crusie and Bob Mayer, who are collaborating on a soon-to-be-released book called Don't Look Down. Crusie writes romantic comedy and Mayer writes action/adventure, so it seems like their collaboration could be interesting. I believe they're calling the project a romantic adventure.
The How it Happened page of their website gives a funny story about how these two writers paired up. Their dueling blog carries on the repartee (and might republish their presentation for RWA Pro). Check it out.