Rekindling a marriage as empty nesters

Now that our kids are gone, what can we do to revitalize our relationship? I thought our marriage was healthy and vibrant – that is, until the last of our three children left home. I realize now that it was the kids who brought life into the house, and that so much of our marriage was centered around them and their activities. Without them, my husband and I are lost. I have too much time on my hands. The two of us have nothing in common, and my husband is spending more time at work and with his buddies so that he doesn't have to deal with our issues. What should I do?