I have been searching for hours looking for a extension to do this and have come up empty. Does anyone know of an extension that will send email updates to registered users when new items are added to a particular k2 category?

I sent you a pm request. I have the same need. pm me and lets talk and see if the needs are similar.
wjwjr

Hello !

I'm looking for the same thing... I need to give the possibility to the registred user to suscribe on a specific category (or/and public user with the possibility to enter there e-mail adress). This registration send automaticaly a e-mail to this users when a new item is posted in the category.

Much better, if the moderator of the category can get back a e-mail when there is a new suscriber...
Also much better if there is a counter that show how many suscribers are following this category in frontend...

I know there is an extensions that make it with joomla 1.5 (K2 multi notify), but I need it for J2.5... I have send a mail to the K2 multi notify developper but I got no reply...

Can you help me ?