jAlbum will do that but your real problem is going to be the fact the DNS-320L does not have the horsepower to be a full blown web-server, especially if you expect a lot of people to view your pictures. Remember that anything out on the web can, and will, be picked up by other people therefore you will also need to be able show that you have the copyright to those pictures and, if you are in the US, comply with the laws regarding age of any persons shown.
If you just want to make them available to family you can use the built in FTP server (there will not be any preview of the images) to do that.