I have always been really interested in grafting as a form of vegetative reproduction. I have heard of people grafting the branches of a pear tree onto an apple tree to create a kind of hybrid fruit. The potential of this seems limitless and I have always been intrigued by what these combined fruits taste like.
It sees like this would work for lots of different fruits. Imagine combining a peach and a plumb. Or a nectarine and an apricot. I could sit here all day and type out intriguing combinations. If I had the means I would try some experiments myself. Unfortunately there is probably not an apple tree within 30 miles of my house and peach trees are even more rare. Hopefully one day I will get a chance to tinker.