Different post date and publishing date?

This will sure sound as a strange request, and it is possible that this can not be done at all. But I’ll make a try anyway.

I enter posts in my log editing the date to that of the event that the post actually talks about. A concert a month ago, a podcast I heard a few weeks ago, whatever. This date is very often not the date in which the actual posts is being published in the blog. I just thought that for the purpose of my weblog, this makes more sense. Events appear order chronologically as they happened, not as they were entered in the blog.

Now, I would like the widget “Recent posts” to reflect the posts recently ADDED to the log regardless of their date. That is, I would like it to display posts according to the dates in which they were actually published (or revised), not the date that I enter manually in each post correpsonding to the event being described.

Is this possible? I relaize that I could do this manually, moving in and out recently added posts from a special category, but it would be much nicer if this could be done automatically. Is there anywhere a place where the “last modified” date of each post is being kept?

Many thnaks in advance.