March: Christina Aguilera
When listing one house isn't enough, some celebs try for a daily double. Take Christina Aguilera, for instance. Aguilera is a high-income earner who can eschew standard real estate advice.
In March, Aguilera listed her Beverly Hills home for $13 million while her Hollywood Hills home continued to linger on the market. While the Hollywood Hills mansion has since sold, Aguilera's Beverly Hills pad — previously owned by the Osbournes — hasn't wooed a buyer yet.