I would like to create a plugin that add Google Chrome Frame support in Sonar. For this I need a way to add a <meta> tag in <head> of every page of Sonar.
I suggest to create a new extension point named org.sonar.api.web.HtmlHeader that allow to put custom content in <head> section.
At the same time you could create a org.sonar.api.web.Header extension point in order to allow adding content just after the <body> element. Il would allow to create a "banner" plugin allowing to add enterprise logo on every page.