First of all... here are some vendors to buy the plain plastic pops from:
There are some other places that sell them, but they sell out QUICKLY. If you think you need these anytime in the foreseeable future... begin looking at buying them NOW! They may not be there when you go searching next time! Try doing a Google search for "push pop containers" and you should find some retailers as well.
OK, so now that you know where to buy them... here are some of the BEST ideas I've seen:
Whimsical Mod Parties
As you can see... there are literally COUNTLESS numbers of things you can do with these push pop containers! You can rest assured that there will be push pops of some sort at Reagan's birthday party as I am beyond excited about these awesome new toys!! Oh, and you can actually make ice cream/sherbert/frozen yogurt in these as well... but why go traditional when you can go so out of the pop?! :0)