Thank you Veltro, couldn't have explained it any better myself.
I'm thinking of providing some space for uploading files, but since this can be easily abused it must be made very secure before I'd commit.
Also its a matter of space. Only after the board settles in a routine will I be able to judge the space it generally requires, the same goes for bandwidth.
One of the options would be temporary special registration/invitation. This might sound like overkill, but I am not paying this service so someone can upload his holliday snaps
The last few days I have been mainly occupied with collecting info to better understand the workings of this phpBB tool, or finding places where this info can be obtained.
There are so many options, from general portal applications, that run the whole site, to specialist photo albums. Right now I was looking at possibly combining such a portal with phpBB (which I believe is possible with PostNuke).