Most years I fly around 40k miles. Never enough to make Gold. I always thought it would be nice for UA to acknowledge those of us who continue to fly UA after we hit 25k/Silver Status even though we'll never make Gold. Or for miles flown after reaching Gold but falling short of Platinum.
I could easily, once I've secured UA Silver, switch to Delta, for example, to pump up miles with that carrier. Even if UA gave us half credit for our 'extra' miles to carry over toward next year's status, it would be a nice perk.

I am now told by a friend that DL does exactly that. She had over 13k miles carry over from 2012 that were applied to her 2013 status. Instead of starting with zero status miles on January 1 she started with 13k miles in the bank that were excess miles after she achieved her status rank but fell short of the next tier.
That's a great incentive for status achieving customers to continue to fly DL, rather than switching carriers once their desired Status level is reached.

UA ought to consider that.