This would be a nice feature for users who register: Give them an option to show theire Name in the "participants List".
They can choose "show nothing", "show only firstname/username", "show firstname, lastname, city" and optionaly put a link to the installed PIM.
There are many options to catch: "Show participants-list only to registered participants", "Show participants-list to guests", "enable communication between participants" and so on.
After the new "Details-Link" I will now link from every event to a description-page. I would like to show up there a list of the signed in participants. So a plugin, that shows a little table with the registered members is a nice feature, because it also is advertisiemtn for the event: People follow people, so if they see plenty of names of users, that are already registered, this motivates them to also register.
I would suggest to built up the table like this:
Set up the table always with as many rows as the capacity of the event. Just leave free places blank. And also don´t hide users, who don´t want to show up. Just hide theire names, so it says "anonymous participant" or something like that. The list should always show how many participants are already signed in.