I'm hosting my own wordpress site for personal use.
I add a lot of attachments to the posts but withing wordpress you can only search for the filenames and not for the content.
Sure you can use the Google Desktop or other GUI based indexing tools but if you want a good web interface you should install xapian-omega.
It's small, fully featured, fast and can index most attachments that are allowed for wordpress usage.
Give it a try.
More info here!