This Newsweek article explains why & how Sandra Day O’Connor has been busy since she left the Court:
[snip]
"After her surprise announcement in July 2005 that she was leaving the court, O’Connor seemed likely to follow most of her former colleagues into a quiet private life. But America’s first female justice is blazing a new path in retirement, too. At 76, O’Connor is still physically and mentally fit. Her current schedule—packed with appeals-court hearings, law-school lectures, speechmaking and book writing—can make her days on the court look practically languorous. And these commitments don’t include her recent work with the Iraq Study Group (or her aerobics classes). She divides her time between Washington, where she maintains her chambers, and Phoenix, where she cares for her husband, John, who suffers from Alzheimer’s. "She just put it in third gear and went on," says her brother, H. Alan Day.
[snip]
"Because O’Connor chose to retire rather than resign, she’s still considered an active judge and draws a salary. So she has responsibilities as an officer of the court to fill in as a judge on appeals courts—a task that requires copious preparation. Even the most mundane duties of judgeship do not escape her: last month she spent two days swearing in public officials in Arizona. Being a judge also means O’Connor can’t cash in on any of the speeches or public appearances she makes. That would change if she resigned. But then, she wouldn’t have an office at the court. Maybe then she would be a nobody. ‘I’d be on my own,’ she says. ‘I have chosen a different route.’"