Prepopulate the Write Post Form?

We use WordPress to power the site for our podcast. We do the podcast four nights a week, and that means we have to make a post almost every day. Much of this post is pointless data entry that could be automated. It would make our lives much easier if we had to do less data entry to make the post.

For example, if the day of the week is Tuesday, then we want the Tuesday category to be selected. If the date is January 23, 2008, we want to add a custom field named mp3 that has the value 012308.mp3. These are just some of the things we could do. Ideally we would be able to pre-populate every field in the entire write post form based on the date.

I can’t seem to find any information about how a wordpress plugin could pre-populate the form fields on the write post page in the admin interface. If someone could just point me in the right direction, I could write the plugin myself.

Thanks