I imagine you can do it in the other browsers, but I've yet to find it - in Maxthon I can set up URL Keys and URL Aliases. The URL Keys are my F buttons, to which can be assigned multiple URLs, which will open when you hit the F button. For example, I have Chrons and another forum assigned to F11, a number of gaming sites assigned to F12, and so on.
A URL Alias is the same, except it's a word or phrase that I type in my address bar to open up the site linked to it. Only one URL per alias, though.