Brand new WordPress plugin Apollo bar works great. You can use it for displaying rotating messages or for publishing simple announcements at the top of your WordPress site. Announcement bar goes off when reader clicks X button.
Installation & Usage:
Install and activate Apollo Bar, then Visit Dashboard -> Settings -> Apollo Bar and check the options: Enable Apollo Bar & Enable Apollo Bar Logo.
Select a color scheme from Blue, Green and Red and click Save button:
Clicking Save buttons adds a new menu Apollo Bar on your Dashboard’s left sidebar. Visit Dashboard -> Apollo Bar -> Add New and add new announcement, just like you add new posts. Set the Scheduling (start and end dates) and click Publish button:
You can manage all your announcements from Dashboard ->Apollo Bar -> All Items.