I really like these molds because they are individual, so they take up less freezer space (if we have eaten 5-6, then the 5 empties get washed and put away, rather than being stuck kn the freezer until we eat the last one:
inhttp://www.amazon.com/gp/aw/d/B000G34F1Q?pc_redir=1400104356&robot_redir=1
As a PP said, you don't really need a recipe. Rule of thumb is: if it tastes good as a smoothie, it'll taste good as a popsicle. That said, my kids love when I make pudding using this recipe:
http://vegan-magic.blogspot.com/2012/09/chocolate-mousse-no-added-sugar.html?m=1
We have pudding for dessert one night, then thin the remaining pudding with a little milk and maple syrup and freeze for the next dessert night.
If you are worried about messes, then putting a little gelatin of agar-agar into the mix will help them melt more slowly, but my main tip is to just plan on having messy kids. I have been known to make my kids eat shirtless on the back patio, if we have somewhere to be later and I want them to be easy to wipe off.