A couple ways to get miles for stuff you are probably already doing and won't cost you anything more:


Continental - get miles for grocery shopping at Shoprite, if you shop there anyways, it's a great way to keep your account active without doing anything but buying groceries.

United and Continental (and probably others) - miles for using a debit card

American (maybe others?) - Miles for paying your electric bill if you use their alternative suppliers.

In my case the debit card will earn me enough for a free trip, the grocery shopping won't, but it will keep the account active by putting in a few hundred miles every three months.