British Airways has a "Premier" tier above its Gold tier. Searching the BA board for "Premier" should bring up a lot of threads related to it.

Other airlines have been known to use special tags/designators such as "VIP" or "CIP" (commercially important person). These tags are part of your record and used for people who do not fly an enormous amount of miles but are people the airline is interested in keeping happy i.e. celebrities,corporate big wigs..etc.