I think what the new contributed Drupal subscriptions module does, if I understand it right, is brilliant: essentially whatever you subscribe to on the site, from your user page you can merge your individual subscriptions as one subscription. Therefore, you can merge subscriptions of similar content and then if you could choose to receive your subscriptions once a week you essentially create your own newsletter.

Right now, when you install the subscription module a global comment subscription is available which lets users subscribe to all comments posted on the site. Though not quite there yet, administrators could also bundle different subscribable content and make these channels available as global channels to which any user can subscribe. If you take this a step further, users could be allowed to make their own subscription bundles which would be public or private and can allow other users to subscribe to their bundles.

On a large community site talking about global economics and general development issues, you could subscribe to only users you know who are economists, or just to economics students, or to three different categories about different microfinance topics and 5 users who specialize in the microfinance field. This way, your bundle would fill up with content from these users’ posts and from anything anyone else posts under your subscribed categories and you could get an email every Sunday morning with all this content bundled together for you. This may be more exacting and personalized than any RSS feed and better than getting 15 emails in one day from different things you subscribed to on a site.