This can be put on a feature list, but as an admin I'd really also like to be able to query (in real-time) the master ban list. If some guy joins my server and acts like a tard, I'd like to know if he's been banned on other servers that I recognize (or trust to be admin'ed well).
Or at the same time, when considering banning someone it'd be worth it to me to see if that player's been banned at other places. A guy who has been banned on no other servers might deserve a little more leniency.
Some sort of realtime query for players/guids/IPs connected to your server would be very useful.
For those of you who probably haven't played on our server (The Potato Patch), you're not aware that we have a "bot' that sits and watches the console and does a number of commands. Wonko, who coded this bot, says it'd be relatively simple to add this query (and other functionality of a master ban list) to the bot. If it helped, we could work to help distribute a copy of the bot designed to interact with the master ban list.
Edit: For anyone thats interested, please stop by The Potato Patch (after working hours) and talk to Wonko and I about it. If you're curious about the bot, you can check out some of the things he can do on our website (
http://potatopatch.brianmoses.net). But the best thing to do is just stop by and we'll show you.