I freeze my over-ripe bananas all the time, and they're great for banana bread, smoothies, and even as is! Like banana ice cream :-)
I was on a smoothie kick for a year, and only drank smoothies for most dinners and lunches. I didn't lose a pound! I didn't realize how many calories are in my smoothies, and I counted them as a "drink", not as a meal. So, if you're drinking lots of smoothies, remember that some of them have as many calories as a meal!