I still log in to OGR (still feels wrong to call it Gateway) and MUS*H a handful of times a month to check the boards. To my knowledge there's still no better social box doing what they do, for better or worse. The embassies on OGR don't seem to be maintained anymore, but benign neglect is maybe preferable to that brief time that crazy person Ra had taken it over.
The MUSH/MUX list on mushcode.com is what I tend to use to find active games.