Interesting trip down Miles memory lane
From 
View from the Wing:
10. Free status offers for  Marriott Gold, Avis Presidents Club (still active…), Virgin Silver,  Hilton Gold, Starwood Gold, Continental Silver just for becoming an  AT&T customer.
9. Class of Service Bonuses on Upgrades (Earn  more bonus miles on United than it took to upgrade US-Hawaii, the  upgrade more than paid for itself).
8. 1-800-Flowers 100 miles per dollar with Delta. On  December 30, 2003 1-800-Flowers sent out an email saying they would  award 100 miles per dollar spent on flowers. Presumably they had bought a  ton of Delta miles which needed to be awarded or else they would  expire. So they thought they would generate some cash with this rapidly  expiring asset. The email was targeted, but anyone could use the  promotion. And it wound up being much bigger than they  anticipated…
7. Double, triple, quadruple bonus dipping  (Continental, US Airways, Priority Club). About 9 years ago some members  earned six-figure mileage flying cross country on Continental. Once  upon a time you could fly a handful of flights and earn Chairmans  Preferred (100,000 mile flyer status) on US Airways. And many folks have  earned several free nights with Priority Club with single night stays.  All because computer systems let folks stack different bonuses — many of  which were targeted for different members, but those same computer  systems didn’t check to see whether the member signing up had actually  been targeted. A double error! Sadly computer systems have gotten more  sophisticated with time.
6. Savings bonds, travelers checks, prepaid visa debit cards.  Over time there have been huge opportunities to buy money with your  mileage earning credit card, at little or not cost, and then pay off  your credit card with the money you purchased. Rinse, repeat. Whether  savings bonds, travelers checks (thanks, AAA!), or visa debit cards  which you then turn into money orders, these eventually get shut down —  because the company offering them winds up eating the credit card  transaction fees without generating real business. But many frequent  flyers have earned many millions of miles. 
5. KLM Status Match and Millions of Free Miles: In  the Fall of 2001, KLM wasn’t just matching status —  they were matching the account balances in your competitor elite account  as well! 
4. LatinPass 1,000,000 Miles: During the first half of 2000, you could earn a  million miles (with the dreaded LatinPass program) for flying a total of  9 international segments on 9 different partner airlines. 
3. InsideFlyer-Starwood. In the Spring of 2002, Randy Petersen was  giving away 2500 Starwood points with each Inside Flyer  magazine subscription. Back then Starwood points converted 1->2 into  Qantas, including bonuses. 52,500 Starwood points yielded Qantas points.  Doing the math, it was possible to buy 21 Inside Flyer  subscriptions, transfer the Starwood points to Qantas, and redeem for  travel on the Concorde. Donate the magazines to charity and further  reduce your cost basis. 
2. Goldpoints/valumags: Around Christmas 2001 it was possible to earn more  than 100 miles per dollar with your choice of several airlines by  purchasing magazine subscriptions from Valumags through the Goldpoints  shopping portal. Some members donated the magazines to non-profits for  the tax deduction, reducing their cost basis even further. 
1. Pudding  Guy. Enough said. The dude is  famous.