There are some old threads on FT about million mile programs, but much of the information in them is obsolete. I thought it would be worthwhile to compile updated information on the various offerings and perhaps create a comparison chart.

Continental: million mile program currently closed to new qualifiers

United: qualification - one million actual flight miles on United, United Shuttle, and United Express; code-shares do not count; Star Alliance flights do not count; reward - lifetime Premier Executive status and three confirmed systemwide upgrades
Questions: Do flights of less than 500 miles add 500 miles or actual miles to the million mile counter? Is there a special level for two-million milers, three-million milers, etc?

Delta: qualification - one million base miles; currently includes actual miles or 500-mile minimum, whichever is greater, on Delta, Delta Connection, AeroMexico, and Air France; old base miles from Austrian, Sabena, and Swissair flights are still included even though those airlines are no longer in the program; reward - lifetime Silver Medallion status, an "exclusive thank-you gift", Million Miler luggage tags and stationery
Questions: Is there a special level for two-million milers, three-million milers, etc?

TWA: qualification - one million flight miles on TWA; reward - lifetime top-tier elite status
Questions: Do flights of less than 750 miles add the minimum miles or actual miles to the million mile counter? Is there a special level for two-million milers, three-million milers, etc? Are code-share flights included?

US Airways: no million mile program (?)

Northwest: qualification - one million base miles; includes elite-qualifying partner airlines; reward - ???
Questions: Do flights of less than 500 miles add 500 miles or actual miles to the million mile counter? Is there a special level for two-million milers, three-million milers, etc? What exactly do million milers get?

What other airlines offer million mile programs? What about KLM, Lufthansa, SAS, Air Canada, etc, etc?