I've been thinking about setting something like this up, but over email. Anyone who opts in to the mailing list would be able to submit a link+description, and once a week some software would automagically send out an aggregated email to everyone who opts in.

The problem is getting it to the optimum size. If it's too small, it won't work because nobody will want to post. If it's too large, then the signal-to-noise ratio drops and it's no better than Reddit or HN.

Also, moderation is hard.