Another example from a debian box:

DBM
        DBI:DBM:f_dir=., DBI:DBM:f_dir=.X11-unix, DBI:DBM:f_dir=.ICE-u
+nix
ExampleP
        dbi:ExampleP:dir=.
File
        DBI:DBM:f_dir=., DBI:DBM:f_dir=.X11-unix, DBI:DBM:f_dir=.ICE-u
+nix
Proxy

Sponge

mysql
[download]

The mysql driver might have been able to find /var/run/mysqld/mysqld.sock, but obviously it didn't. And I have to confess I don't know why .X11-unix and .ICE-unix (I guess this referes to the socket dirs in /tmp) turned up as DBM data sources