Doomseeker is a server browser for client/server source ports, available for Windows, Linux and MacOS X. It supports Skulltag, Odamex, ZDaemon, Vavoom and Chocolate Doom through individual plugins. In addition to this, it is bundled with Zandronum as a primary resource. The user can only join servers if they have the applicable IWADs, all other PWADs will automatically downloaded with no user intervention. It's currently among the more used server browsers for Dooming.
DoomSeeker Server Browser