Twitter has recently added a Election 2008 topic bar covering key tweet topics around the forthcoming US presidential election to the top of the site. While you can minimise this by clicking on the X at the right, the setting isn't permanent -- so every time you change pages or click on Home to refresh, it returns. Fortunately, as the Get Satisfaction forum explains, Firefox users running the free AdBlock Plus extension can banish the bar permanently.
To install AdBlock Plus if you don't have it, just search for it from the Add-ons option, found under the Tools menu. Once it's installed, selected Tools, select Add-ons, select AdBlock Plus and click Options. Click on Add filter and paste in the following code snippet:
OK your way out of there, and Twitter will have a clean appearance once again.