We were in upstate New York a few weeks ago, and spent a productive hour picking a large container of blueberries, and of course we ate them all within a matter of a few days. We are crazy blueberry people!
However, there's an easy way to make that bounty last as summer fades away. DO NOT WASH the blueberries before taking this step! Just spread them on a cookie sheet and stick in the freezer. Once they are frozen individually, dump them into a freezer-safe plastic Ziploc bag. They will keep for months in the freezer, and they can easily be measured out for muffins, pancakes, smoothies, etc.