The three things I'd be most interested in seeing are:

1. A fine-tuned model for structured data extraction. Get something that's REALLY good at outputting in a specific JSON format, then show it running against a wide range of weird inputs.

2. A fine-tuned vision LLM that gains a new ability that the underlying model did not have, such as identifying different breeds of common California garden birds

3. Text to SQL. Text to SQL is always a great demo for this stuff, a fine-tuned model that's demonstrably "better" at text to SQL for a specific complex database schema would be a really great example.