1) You may want functionality similar to saved listings but with subcategories for organization ("saved listings" has no subcategories, it's just a list). You can let people add existing listings from your directory into their personal listings list and its subcategories using this template code (a good place to put it is in the listing bit, Admin Panel -> Themes -> Manage Templates -> "Sub-Templates" -> "Listing Bit"):
<IF {TID} does not contain albums>
<form action="albums.php?add={LINKID}" method="post">
Add to <select name="subalbumid">{THISMEMBERALBUMLIST}</select>
<input type="submit" value="Add" >
</form>
</IF>
<form action="albums.php?add={LINKID}" method="post">
Add to <select name="subalbumid">{THISMEMBERALBUMLIST}</select>
<input type="submit" value="Add" >
</form>
</IF>
Or if you don't want to involve subcategories a simple link:
<a href="albums.php?add={LINKID}">Add this listing to list</a>
To allow people to remove a listing from their list, place this by it:
<IF {TID} contains albums><a href="albums.php?todo=remove&linkid={LINKID}&catid={LINKCATID}">Remove</a></IF>
Thanks to the conditionals, you can put these in the listing bit and the add form will only show outside of the personal listings list while the remove link will only show inside the personal listings list.
2) You may want to let people add new listings that aren't in the directory. This is mostly useful for WSN Gallery, where members can have their own personal albums of their own images which aren't mixed with the site's images (you can even use your WSN Gallery as an add-on for a forum giving forum members each a gallery, when integrated with the forum member system). You may perhaps find use for it in the other scripts too.