Well, you could create an additional blog and possibly make it hidden from view (that would depend on what works best for you) and in that blog create a category that is specifically for those files you'll offer for download. Then use the "sideblog plugin" to have the contents of that category display in the sidebar of your main blog. You could set it up so that only the most recent 3 or 5 or 8 or whatever entries get displayed on the main blog... Then just create a folder in your site structure to hold those files, and link them from the posts that get displayed in the sidebar...

jj.

Here is the link to the Sideblog Plugin mentioned by jibberjab: http://brendoman.com/dbc/2006/07/12/sideblog_plugin_for_b2evolution