Thanks for the kind words, Dave.
My thought would be a two part extension... one for front-end and one for back-end. The back-end would really be the same technology as Data Assist - just with the necessary items for the blog pages - so it would create a blog results page and add/update pages with the necessary items for date, tags, categories, etc.
The front-end would be similar to CSS Form Builder allowing you to pick which elements you want and perhaps a few pre-built CSS styles for the blog.
Cheers,
Brian