http://metacool.typepad.com/metacool/2009/10/what-are-you-going-to-do-today.html
... prototype some business scenarios.
... prototype a business plan.
... finish a paper.
Not a windmill, but important to me.
Thanks Diego for the link. It was inspiring and a good reminder to check myself against the cult of done:
http://www.brepettis.com/blog/2009/3/3/the-cult-of-done-manifesto.html