Horizontal tabs. Most browsers display tabs horizontally, at the top of the window. However, as their number increases, tabs become difficult to handle: They grow narrower and less of their title is displayed. And figuring out which tabs are related becomes harder, for example, which tabs were opened from the same page.
Vertical tabs. The obvious fix is to display tabs vertically. With wide screens being ubiquitous, horizontal space is more readily available than vertical space, so putting tabs there makes more sense. Additionally, if many tabs are open, one simply scrolls vertically, which is more natural than scrolling horizontally. And the tabs remain wide, their titles remain readable. The Firefox add-on “Tree Style Tab” provides one more service: It shows tabs as a tree (which you are free to rearrange) and makes new tabs the children of the tabs from which they were opened. That imposes some immediate order that is very useful. Reader rsanchez1 points out that Opera has another solution: A Tab Stack is a group of tabs that is created by dragging one tab onto another one.
Current browsers implement one more helpful measure: Background tabs receive a greatly reduced amount of processing power. That is very noticeable under Firefox 10 which handles many open tabs gracefully, where previous versions slowed down the complete system.
Simple bookmarking. Idea: Instead of the current forest, manage bookmarks as a stream that is ordered chronologically by date of last visit (inspiration: Gelernter’s lifestreams [1]). In order to bookmark a tab, you click on a star that appears when you hover above it. A modifier key allows you to star and close a tab at the same time. Another modifier key lets you additionally add tags. They can be quickly entered as a single comma-separated text string. Tagging is faster than placing a bookmark in a folder, because coming up with a tag name is faster than finding a folder. This process also lends itself well to keyboard navigation: Switch between tabs with Alt-Tab (Ctrl-Tab on Macs), hit a shortcut to close and tag, enter a single line of tags, hit return and be done.
It is important that simple bookmarking be complemented by powerful navigation features, such as “descending” into a tag: Text searches will only be among bookmarks that have the tag; the tags displayed for additional filtering will only be those that exist among the currently displayed bookmarks. The browsing history would include the tagged bookmarks and have more structure. There is much research on how to improve navigation and management of tagged entities, all of which applies here. Note that Firefox already supports most of this style of bookmarking, including tags. But it is still limited when it comes to navigating and managing those bookmarks.
Too many bookmarks? If our inboxes and to-do lists are any indication then simple bookmarking would result in many bookmarks that you will never look at again. That phenomenon is a fact of life. To help, we take a cue from the brain and introduce aging (“forgetting”) to bookmarks: Bookmarks that haven’t been visited in a long time are considered less relevant. That relevancy will influence browsing (where more recent bookmarks show up first) and search (where older bookmarks are ranked lower). Aging is complemented by manual prioritization via tags: a tag “todo” will have more importance to a user than a tag “might read later”. But technical features can only go so far, a mental shift is required, as well: Users will have to accept that they will never revisit all of their bookmarks, they will have to become gracious about forgetting them.