I’m trying to setup ad-hoc small mailing lists using GMail. They have a contact groups feature that mostly does what I need. However, the interface for adding contacts is quite limited - you pick from a list.
It’d make a lot more sense to allow addition of contacts to groups based on searching - eg. look for everyone labeled “tester” and add them to the “tester” contact group en-masse, or for any message containing the term “paintball” and add all the senders/recipients to “paintballers” group.
So there you go GMail group, please get to work.