One thing that has always bugged me when running a dedicated l4d serv is that there is no way to connect via lobby without having everyone set a sv_searchstring.
I was thinking that when you DO join a dedicated serv through standard match making and a game ends the server will return all players to the lobby.
Would it be possible to write a plugin that when the number of players is 0 and someone joins it automatically set's their sv_searchstring and sends them to a lobby? It would mean that the first person to join would have to load a map only to exit it... but it would also allow non-technical people to force specific servers from matchmaking without having to access the dev console.
I just like being able to choose my char/map/difficulty before playing and without admin but still want to use my own serv.