Have we found any decent use of souls outside of necromancy?

I'm looking into this... and I think if I were to take the souls of great wizards and imbue them into my swamp I could give my swamp an automated defense, think fireballing knights who walk in, or entangling thieves trying to steal from me.

I feel this could be quite the improvement regarding souls, as about 99% of the time it's just necromancy.

Any other wizards or witches devise ways to use souls in more... ethical ways?