Dont forget to tell them about the new fee for transfering from DC to airline miles!!!!
<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Beckles:
You can transfer miles from United to Diners Club then to Delta, but you'll lose 50% of the value.
Obligatory Diners Club Plug
https://www.citibank.com/dinersus/mgm/apply/index.htm
Sponsor Code: SSKE4975
You also get 12,000 miles for signing up (1,000 per month that you make a charge, just make sure to buy some gas at a gas station that takes DC), and if you're nice enough to use my Sponsor Code above I'll get a couple thousand miles. 
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