Here are some visual ideas for an activity map (posts per period), large breaks in time and most-liked posts.
It feels like there’s wasted space to the right of the line, but I don’t see how you can put any other UI elements there without them being obscured by the sliding date.
or maybe have a more dynamic indicator to show the “hotness” of a topic, like this drupal module does. It shows a color gauge for “hotness” of a topic, which has some decay settings and other parameters which change the color based on clicks, views, etc.
Like this. Could include bookmarks. The chapters could be breaks in the line.
A fuzzy time concept.
There is also the possibility of the line not reflecting posts but have a fuzzy timeline 
. So where things are more popular the time can stretch out to more details. Where posts are less popular one unit on the time line can represent more posts.
This could for example break time into units of equal number of views / likes. Managing scrolling in that way.
Overall, I like the ideas there, but I would lose the bar graph part of this:
The break in the line is more interesting than seeing the relative activity. The lack of units on either dimension of the bar graph is a big negative.
I am definitely warming up to “show me my explicit bookmarks in the timeline”. Particularly on a long topic, there ought to be some way to navigate via time breaks or explicit bookmarks directly.
The other thing I’d really like to see is a marker for my last read post. So if I enter a topic via a link to a specific post, I can easily jump to the new stuff.
Isn’t this what the back button does?
That already exists right now today, so you are proposing… what we already do.
It existed, I saw it when the bar came out. But it seems to have gone away. As in, I haven’t seen it today in this topic or others. If removing it was not deliberate, then there is a bug.
Sure it works. Enter a topic where:
Basically, enter a topic you have previously entered, that has unread replies – but enter at the top not at your last read position. You can do this a few different ways, search, or click the reply count in the topic list, like so:
Another way to do it is enter at your current read position and then scroll up a fair bit.
TL;DR Discourse does such a good job of always placing you at your current read position that you may rarely see the “back” button in the timeline.
- you hold a read position
That’s probably why it did not work for me here. But I can state with 100% certainty that I’ve seen it fail to appear on other Discourse installs. It’s possible they’ve done something to break it.
Today, I got a new like in a topic I have not read or posted in for several days. I entered by following the like notification. There were at least two new posts, out of a reasonable less than 30 posts, and no “Back”. And since I’ve posted there, it is a definite that that I am Tracking and hold a read position.
Because there was a deleted post most likely.
What about the ability for users (or certain trust levels) to add a tag-like “flare” to a post that will show up in the timeline and let you jump to those posts.
E.g. A long support thread could have multiple posts with a “solution” flare that a user could quickly click through in the timeline instead of reading through the entire thread. Kind of like the Discourse Solved plugin, but more customizable (different “flares”) and accisbble by users other than the OP. Another addition could be the ability for other users to agree (add a + next to the flare) or disagree (a - next to the flare) to place more emphasis on the more important flares/posts in that thread which could be useful if there are multiple flares in a long thread.
Maybe likes and bookmarks would be a good place to start since those already exist?
Big time gaps is where this is most needed at the moment IMO but the case for bookmarks and things similar to bookmarks is strong as well.
Regarding the scrollbar itself - profile icons to “pop” in and out of view as you scroll, indicating a highly fav’d post. The animation of it fading it/out as you scroll (alternately, the bubble pop-style animation) would be great to catch the eye and halt a person skimming that might want to zero in on a really great response.
@codinghorror asked me over email “So only when scrolling?” My gut says yes, two points:
Dunno how frequently this might happen, but what happens when the density of really great posts shoots the roof? We’re talking about tons of little profile icons jammed into that scrollbar at various places. I predict noise and ugliness. Hard to have a few of them stand out during the scroll (though with UX mastery it could be done!)
I see where you’re going with this, and I think the fade in/out during scroll when passing the post would really catch the eye and be a good way to redirect attention to the post where a reader might otherwise skip. BUT…you could do this: when not scrolling and just staring at the bar, you could offer (VERY) subtle dots that reflect mass-fav’d posts along the way. Then, during the scroll, those dots burst into a little profile bubble animation, growing as you near/drag over them, then shrinking back to dots as you pass by.
I like @elijah’s image for this, in his reply above. He’s nailed it with the dots, so replace the perma-hearts with “pop” animations of profile icons as the user scrolls, indicating the person responsible for the fantabulous post.
What if the dots also had a hover action? Obviously this doesn’t work on mobile, but I like to be able to see what the dot is for without needing to scroll and potentially change my spot on the topic.
Credit where credit is due: I was just suggesting a change to @Tom_Newsom’s mock-up.
