What are some of the more obscure requirements people have on data grids?

Well not really obscure, but some want formulas, some want advanced filters, grouping/pivoting. Nothing that's not done before but you don't want to say yes to all these things as the product will lose its core identity and strength.

So I will release my new data grid component based on my own toolkit, and if people want tweaks or "add these features", I will demonstrate them the toolkit.