For these instances, cake mixes work wonderfully. One of the reasons they work so well is not just because they're pre-packaged, but because they're versatile! I Googled extensively on how to manipulate cake mixes into interesting creations. I didn't find as much as I expected.
In order to increase the doctoring-cake-mix database the Interweb, I thought I'd start adding some of my recipes. I made these pina colada bars for a friend's bake sale, and apparently they sold out first, if that says anything.