To be honest, I doubt that anyone will tell you exactly which sticky content works well – if it’s copied, it’s no longer unique!
You know good content when you see it – it makes you think ‘I wish I’d thought of that!’
Golden rule: design for users. Ask yourself – as a user – what’s missing? What do I have to trawl around the web to find? What would I love to see? Then go ahead and design it.
It’s hard to find niches in this industry, but as you said Jackpot Graphs is a great idea. There must be more out there!