OldWeb

It's fairly open ended. Members can post whatever they like (within certain boundaries). Some people post more text. Others post mostly links with just a little text. It seem like the sweet spot is somewhere in the middle, where a post would be a few sentences explaining something with key terms linked out to some relevant links. Really cool way to get exposure to things I would have otherwise never encountered and to share your own niche interests. As a member, you can post a single front-page post every 24 hours.

Here's what they have to say about it:

A good post to MetaFilter is something that meets the following criteria: most people haven't seen it before, there is something interesting about the content on the page, and it might warrant discussion from others. Posts shouldn't be terribly long, and they don't have to contain multiple links or end with a discussion-sparking question.

I have found their "Ask" sub-site really helpful in the past.