Guest posting without registering, without even knowing

I know that title must sound a little strange, so let me explain a little more clearly the plugin/hack/workaround I’m looking for.

I’d like to create a page (or Page, whatever works best) on my site where, in my case, random visitors could submit upcoming events from a form on that page. However, unbeknowst to them, they would really be posting to WordPress under the name “Guest” and in the category “Events”.

They would never actually log in, or ever have anything to do with the WordPress interface. The “Guest” username and “Events” category would just be passed through to WordPress through hidden form fields or something similar.

The advantage to me would be that I could manage everyone’s posts in WordPress, without having to create some entirely new interface just for that section of my site.

The only problem on my end as far as actually figuring this one out is that the PHP code in post.php is, to me, a big ‘ol mess, in which I have no idea what’s going on.

So, any ideas? Is this even a good/safe idea? Thanks for your help in advance.