I've been searching for a while now but I can't find a definitive answer.
I can't find a way to embed images into posts. Ideally like the vanillaforums.org posting box, which has a photo button, which gives a pop-up with "Enter image URL:". Which plugin is this?
it's the Button Bar plugin. Here is a discussion that talks about it and how to simplify it.
Also, after installing the plugin, go to this link and replace all three files provided by Mark O'Sullivan to make the Button Bar actually embedded within the text box, not hovering over the top. This will also initiate the pop-up you are referring to.
Thanks! I'll check that out