There's a whole forum about it:

https://www.flyertalk.com/forum/manu...-spending-719/

Still sitting on a pile of AA miles from quick churning the Citi Executive AAdvantage World Elite Mastercard with 100k bonus. Even though my original dreams of cashing them in on an EY F vacation have given way to less luxurious travel over the past 5 years, that brief period before the anti-churn rule change stands as my high-water mark in terms of miles accrual.

Personal favorites:

- AirTran (RIP) "Wendy's cups for tickets" scheme in 2006. I was buying hundreds from dumpster-divers on Craigslist and giving everyone in my family 32 flight credits (worth 2 RT tickets). It also got me to "lifetime AIrTran elite status", a program they revoked the following year.

- Travelers Advantage (RIP) in 1997-2001 or so. A travel agent that would rebate 5-10% commissions back to you in the form of a monthly check. I was getting $1,000+ monthly rebates, as I was on the road 200+ days a year.

- ValueAmerica.com (RIP) sale of gift certificates at 70-80 cents on the dollar, depending on how many you would buy. I would book my travel with Travelers Advantage and then pay at checkout with heavily discounted Hyatt gift cards. Another $1,000+ per month in cash back.

Credit card churning.

Citi AA cards every couple of months, Barclays US Air card every few months, 2 different Citi Hilton cards every 67-90 days, 5 or 6 new Chase cards every year, repeat AmEx bonuses for the same card every year, 2 Bank of America Alaska at the same time, 20 new cards a year, a dozen applications at the same time.

Oh yeah, BankDirect/Bask Bank/Texas Capital Bank, fortunately not yet a distant memory.