I've enjoyed this recipe for Blueberry Peach Galette
For recipes using them separately, I am a huge fan of the Peach Frozen Yogurt recipe in David Lebovitz's book The Perfect Scoop (you may be able to get this from your library if you don't have it) and Cook's Illustrated's Creamy Blueberry Sorbet.
CI's Creamy Blueberry Sorbet
2 ½ cups fresh blueberries, pureed with 1/2 cup water
1 cup granulated sugar
2 tablespoons fresh lemon juice
1 tablespoon vodka, good quality
Combine everything in a bowl and stir on and off for several minutes, allowing the sugar to dissolve. Refrigerate until thoroughly chilled. Churn in an ice-cream maker according to the manufacturer's directions.
After churning you can freeze for a few hours to allow it to firm up, but I like the texture best right away.
You can also make a blueberry-maple sauce for pancakes, waffles, or french toast by cooking up some blueberries and maple syrup together, with a pinch of salt, until thick, purple, and syrupy.