I'm going to have to try more things, I can tell...
Meanwhile, I can share with you what I have done...

Last year, I planted a piece of sprouting ginger in with my christmas cactus - this poor thing had been barely saved from that gnat that likes to attack and drain all the life out of the poor thing. I put the ginger there because I didn't have another pot at the time, and I figured that they're both tropical and probably would appreciate the same growing conditions.
Not only is the ginger growing really well, but I have not had a repeat attack of that gnat in all that time, I think the two things are related. :-)

I also have put the pits of some champagne mango pits into a pot this week, I'm eager to see how they do.

I'm aware that sweet potatoes can be a fickle thing because the distributors often treat even the organic ones with something to prevent them from sprouting. Well, this year, we got a couple from a food bank and they started sprouting, so I quickly threw them into a bucket where they are very happily growing. I promise to grab some pictures very soon.