What about the great OnePass---->Amtrak----->United caper circa 2002? You could double-transfer miles at 1:1 back when those airlines were separate and CO had many more complaints about redemptions. I moved some 275K before they limited and then stopped it, and used the UA miles to fly around the south Pacific on NZ awards. My great masterpiece was a 7-ticket odyssey in summer 2006.

Also, around 2000 when I started there were all these codes bouncing around where you'd call CO and have them appended to your account. Like the HYE0 "Hyatt bonus" that didn't require Hyatt stays. I checked my account and had 40K extra miles (keyed to flight segments) posted one day just because of that.

RDM earning was of course much better then in coach, and so were some of the award sales: CO at 20K RT to DUS and 25K to HKG, and DL at 40K to BKK.