After years of waiting for web software to allow collaborative editing of documents like the ones I produce for Aoidoi.org, I finally gave up and wrote an extension to MediaWiki, the software that runs Wikipedia.
Testing of the extension is done, so now there's Scholiastae.org. You can see an example of the output — and the markup from the "view source" tab — for Catullus 48.
There aren't many texts there yet. I have a few works of Lucian I will be working up in the next few weeks, but of course I hope other people will be moved to create an account and add and comment upon works.