I think it would be fun that if you owned more than one garden gnome, you could set up multiple gnomes to talk to each other. I currently own two garden gnomes (I live at 2144 Lavu Lane Quarter, Andra, Ur if you'd like to see them), and I had them learn phrases in an attempt to "insult swordfight." If you're familiar with the Lucasarts classic "The Secret of Monkey Island," you'll be familiar with this concept, and if you're not, you can check out this link. I'd like it so my two gnomes could successfully be set up for one (let's call him Guybrush) to issue an insult at the other (let's call him Lechuck). It would be nice if when Lechuck said to Guybrush, "You fight like a dairy farmer," that he would respond with "How appropriate, you fight like a cow." Right now my gnomes will occasionally say the correct insult and comeback at the same time, but it is random, of course.
Obviously, this idea wouldn't only need to apply to "insult swordfighting"-- it's just an example! Imagine having three or four or more gnomes set up having a grand conversation! It could be fun, I think.