99% of the world's "semi-structured" data is not in Microformats but in tables in spreadsheets.
Wildly inaccurate estimate I'm sure. But I'll bet it dwarfs XML formats including RSS. So where's the Yahoo Pipes for CSV and spreadsheet data? The mashing, pivot-tabling, cartesian joining of live grids?
Yahoo Pipes does have a CSV reader ... but I'd like to see more. Particularly pivoting and SQL-like selects, projects and joins.