[TheLastSuperman]

So you want to know if a mod already exist that; When you hover over a members usergroup title in posts, it will show a popup box with an entire list of the members within said group?

If that is the case, it might not be best to do this... perhaps but if you realize why it's best to not show all usergroups members from all usergroups on the memberlist then you'd realize why that is unless it queries the members on click i.e. at time of request instead of loading for that div area each page load. I dunno I'm split on this, if you should be doing this based on what I know and if it can be done differently... perhaps someone else will come along with some suggestions or info I'm just not considering now so stand by .

Edit: But to answer your question, no I haven't seen anything similar to this but there's so many mods out there I don't know them all, 90% sure but the other 10% is still new to me .