How to create a groups site?

Like yahoo groups or google groups

[coopersita]

I'd like to create a new community site, but I'd like to build it similar to yahoo groups, so people can create a group who they own, and then invite people to join their group.

I've looked into some CMSs but haven't quite found an open source, php/mysql script to do this.

Does anyone knows of a good script to create a community like that?

[YLinc]

Try this script [greatcircle.com...]

It's in Perl. I haven't tried it myself, but was highly advised by my friend.

[coopersita]

I guess it's sort of like that, but web based. majordomo is e-mail based.

Each group would have forums, share files, etc.