Often, it happens with laundry--I'll wash a load before running off to class, or to work, or... well, it really doesn't matter, does it! And then I'll forget it's in there and it will be a day or so before I remember that it's in there and that I need to dry it. By that time, it smells kind of... off.
Solution? Run the wash again with some white vinegar in there along with the detergent. It fixes the smell and when they're done drying, you don't even smell the vinegar. Works for me!
Be sure to check for other great tips at Rocks in My Dryer.