I would suggest the Internet Archive as a good permanent online home for these sorts of things. You can include lots of metadata, and easily link to and from other places on the web. The IA is a non-profit organisation that aims at long-term preservation of digital items.
If someone makes a copyright claim against one of your items, it may be taken down — but this is reasonably unlikely with most genealogical material, I think.
The other site I'd consider is Figshare, which is a commercial academically-oriented open access digital archive. Again, good support for metadata and searchability, and your items will be assigned a DOI for easier citability.
Lastly, as another answer suggests, Flickr is a pretty great place for photos. The original file is stored and can be made available to everyone, and there's good metadata (including Creative Commons licencing, with explicit Public Domain too). I'd avoid using Flickr for documents though, as there are other better places for these.