There is a list for general discussion of things related to the Applications Area of IETF. The address of the list is discuss@apps.ietf.org. To subscribe, send mail to discuss-REQUEST@apps.ietf.org asking to be added to the list. There are also online archives for this list.
A list of chartered Applications Area working groups with pointers to their mailing lists, can be found on the main IETF web server.
Other mailing lists that might be of interest to Applications Area folks are listed below. Note that these lists are not official IETF activities (even though some of the include ietf in their names). Some of them might someday be chartered as IETF working groups, while others will never be IETF working groups. These groups are listed because you think you might be interested in them, but being listed here isn't intended as any kind of endorsement.
Please send updates, corrections, etc. to webmaster@mail.apps.ietf.org.