Tumblr is much smarter about this, and “freezes” your dashboard as you read through it. When you navigate to the next page, you see the next group of posts without repeats. New posts don’t show up (and “push” everything down) until you refresh the dashboard home.
This is what the big numbers in Dashboard page URLs are for (/dashboard/2/80000000). I always love the (rare) times when people notice this because it was my baby. David hates ugly URLs, so this was one of those ideas I couldn’t just bring up while brainstorming — instead, I just implemented it one afternoon in development and said, “Hey, let me show you something cool.”
It’s one of the little things we’ve picked up over time, like aggressively giving every checkbox a clickable <label> or letting the registration form behave like a login form (go ahead, try it), that so many web apps should do if they can. It’s all about the little things.
We need a place to find and share these sorts of ideas.