BrowserSpy.dk shows you just how much information can be retrieved from your browser just by visiting a page.
Available tests are listed below.
HTTP Header Information
Which headers does your browser send? When communicating with the webserver, your browser sends a list of headers. These headers can contain information about which type of images are supported, which kind of documents are supported, the character sets that are acceptable, cookies etc.
|HTTP_ACCEPT_ENCODING||x-gzip, gzip, deflate|