I've just released the elFinder plugin for Cotonti. See the plugin page for more details.
Use this topic to post your feedback on the plugin.
It hasn't been tested properly yet, so report bugs here if you find them. I'll fix them in a few days.
You can also request some features, though I can't promise I can implement them all. For example, I can't change elFinder behavior itself. And I can't make it paste file URL in the page file field (but I'll try to implement it a bit later). There is already one thing in my TODO list for this plug: add a global tag to insert a button that opens elFinder dialog anywhere on site.