BuddyPress.org

@DJPaul‘s plugin https://wordpress.org/extend/plugins/welcome-pack/ – working well in BP 1.2.4.1

There is the Members Widget which shows the “Newest” “Active” and “Popular” Members, then add a text widget on top of that to welcome members.

Plus you could always add this code in home page and style accordingly – http://wordpress.pastebin.com/Rvx4ZgWF – change title and avatar sizes to taste