I stick my head in on Baen’s Bar regularly (http://bar.baen.com), but I don’t have (and don’t want) a conference of my own. I’ll generally find a question or comment with the words David Drake in it on the bar and respond to it.
In addition, there’s a fan-run site that my webmaster looks in on, but I don’t do so myself. (I have the wrong personality for that sort of thing.)
There is also now a David Drake fan club on Facebook, organized by fans.
I’ll cheerfully answer any question put to me e-mailed from the contact form, and anything I say to anybody is said for publication if that person wants to publish it.