Import Legacy Media lets you import files on your server into the WP Media Library.
The import lists all the files and folders in your web-site home directory.
Navigate to sub-folders by clicking on 'folder' links.
Files already in the Media Library are shown without a tickbox. Filters at the top of the file listing allow you to tick all the files, or just editable files. You can then also choose to untick 'old thumbnail' files.
If there are other filters on file selection you would like to see, let me know on the WP Forums.
Files are imported with Title and Description data taken from (in order of precedence) ID3 tags, EXIF data, or the filename.
Once you have selected the files you want imported click the 'Import Files' button.
(This plugin comes complete with the getID3 PHP library in a sub-folder. The library can be found at http://www.getid3.org/.)
0.1 - Just starting out, something to get it working