You can also keep your accounts alive [active] every three years (or whatever the expiration period on the account might be under the terms and conditions) by transferring 1000 miles from points-earning cards such as the Starwood AmEx or Diners Club. Many find it a good idea to keep one's "orphan" accounts alive. You never know when they may come in handy.
Eventually, you could "top off" your account with such a card to redeem an award in a decade or so. (!)
See, e.g.
http://www.citibank.com/dinersus/mgm
If you decide to apply for a Diners Club and don't have anyone else in mind to give the free sponsor bonus points to (no cost to enrollee), my sponsor code is in my profile.
[Link edit.]
[This message has been edited by SPN Lifer (edited 11-25-2002).]