Thanks for this one, this is all I want except one thing: I can't fill in any days earlier than the current month. For one month I've been avoiding some foods I'm mildly allergic to, and in this page I can only click X-s back to the beginning of August. I can live with that, though.
I clicked on the habitcal.com link above and ran away quickly. I'd plow through the wall of text if there wasn't an alternative that's simple as pie.
TBH I'm not looking forward anything with any more features. I'd even remove the 'today' highlight so the timezone combo could go too.