You can add a logo to display next to your properties when they show up in search results. You can do this by logging into your control panel. Once logged in, hover your mouse over the 'Account Setup' option on the top Navigation bar. From the drop down menu select 'General Setup'. At the bottom of the resulting page will be a drop down menu where you can 'Enter Photo URL' or 'Upload Photo.'
The Logo is limited to 100x100 pixels maximum width and height.