Dave Walker spots the flaw in Memeorandum:

The same dozen or so bloggers who only link to each other have been going on and on about Memeorandum for the last few months, and I’ve never really figured out why. I’ve never actually seen anything pop up there that wasn’t already being beaten to death by that same list of people -- if you’re looking for current stuff that’s worth a look I still think you’re better served by del.icio.us or digg or your own aggregator.

I don't think I'd consciously noticed that, but it's true. That's a function of Memeorandum's design - the site ranks a manually selected set of sources pretty high, and that's how it finds things. Here's the explanation from awhile back::

Fortunately, Robert Scoble has more info in his review here, having viewed the site in testing apparently for several months. The service uses a white list of tech and political blogs and then builds out inclusion of other sources based on what they link to. That can include other blogs or more traditional news sources.

That generates the "in crowd" set of links that Dave complains about. Like him, I find that I like Digg a lot. Like Slashdot, it picks up a bunch of stuff I don't really care about that much, but it does seem to hit a wider diversity of material than Memeorandum. They both serve a purpose - but knowing how they work helps me decide which to pay more attention to.