I don't know if this is already in, or if people would want this if it isn't. However, I think having the ability to embed an album would be quite cool. Something like how imgur does it. All the pictures within that album can be embedded into a slideshow on a forum post.
Just tried out a demo of XMG hoping this feature would exist and the lack of the ability to embed an album into a post/thread puts me on the fence.
I run a sports community and we get photo credentials to cover events. We typically just upload the images into a directory on a web server then use the IMG tag to embed ~100 images into a single "photo" thread dedicated for the event however this looks really clunky and requires users to scroll down a long way to view all images. Was hoping that there was an addon that would allow embedding a set of photos into a single post (via a slider or some other mechanism).