One alternative view on history that I think could be very useful, is a graph showing not just where I was, but also how I got there and where I went. It happens fairly often that I remember reading something through, say, HN, but I have no clue where the actual post was. Right now the best solution is to search for related words in my history and hope there isn't too much noise, or to search the site I remember coming from. That's incredibly suboptimal.

In fact, this is probably the reason I like Tree Style Tab[1] so much. Instead of a simple list, it shows my tabs in the context I opened them from.

[1]: https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...

Let's expand that further.

I would like to do a custom search of the content of sites that I have visited.

Oftentimes, I'll remember I read something in the past few days, then it's a mad scramble to open various links to try to figure out if it's the right one.