When you're viewing your own user page, there are now two other "tabs" available, one for showing only topics that you've posted, and one for only comments. These pages are paginated, so you can go back through your whole history of topics/comments. I also intend to make the "recent activity" view paginated as well, but that's a tiny bit more complicated, so I left it out for now.
I plan to extend the tabs/pagination to all user pages some time next week, but as I previously promised, I wanted to give people at least a few days to be able to review their own posts and go back and see if there's anything they want to edit/delete before other users can more easily look through their posts.
This leads into a discussion that I want to have about whether we should do anything special to hide user history.
In general, I think that showing user history is good. It's valuable from an accountability perspective and it has a lot of legitimate benefits. If I run across a user that consistently makes good posts, it's nice to be able to look at their history and see some of the other comments they've made. Maybe (once the site is larger, anyway), I'll even learn about some new groups that I'm interested in by seeing where that user hangs out.
However, there are also obvious downsides, and we're seeing some major demonstrations of this in the media lately (mostly applied to Twitter). I don't want to get into the individual cases, but there have been repeated instances of people digging up years-old tweets and using them as ways to attack people. The main problem with this is that a full history (especially when combined with search) makes it very easy to find things to shame people about, especially when they're pulled entirely out of context of how they were written in the first place.
Tildes is still very new, but this is a real possibility as the site goes on. Do we want people to be able to easily dig up old comments a user made 5+ years ago? Do the potential downsides of that ability outweigh the benefits from being able to easily look back through a user's history?
One other thing to keep in mind is that once the site is publicly visible (and especially once there's an API), there will be external databases of everyone's posts. We can make it more difficult/inconvenient for people to be able to search/review user history, but we can't make it impossible. There's just no way to do that with a site where your posts are public.
Let me know your thoughts, it's a really difficult subject and one that I've been thinking about a lot myself as more and more of these "person in spotlight has embarrassing social media history" cases come up.