There's not one here on FlyerTalk, but on Randy's sister site, WebFlyer, there was an article in the June 1999 issue you might find interesting.

http://www.webflyer.com/@flyer/arcdom/jun99/coverc.htm

For United, 1,000,000 actual flight miles (bonuses don't count) get's you Lifetime Premier Executive level, which is their normally 50,000 annual flight mile tier (second level from the top).