I first noticed this feature in the Opera browser actually, where it has been built in for some years now. After I switched to Firefox I was quite happy to find that there is an addon to add this functionality called Mouse Gestures. After installing it, it allows you to control functions like "back" and "forward", cycling through tabs and even opening bookmarks.
If you go to the options you can choose to have a trail option, showing you the actual gesture you are making, by marking it on screen. The trail is quite extensively customizable, so you can change it to reflect your theme, a nice and thoughtful touch. You can also set up things like minimum gesture size and time-out intervals, activation buttons and so on, take a look at the options page.
Navigating back and forth
Going backwards to the previous page and forward to the next page is really easy. By default you just press and hold the right mouse button and slide the mouse left (for back) or right (for forward). You can customize the button you want to press, it even accommodates left handed people.
Rocker gestures
Rocker gestures use a mouse button and the mouse wheel. If you have rocker gestures enabled, you can cycle through tabs by holding down the right mouse button and scrolling up and down.
Opening bookmarks
This is one of the most clever features of Mouse Gestures, by performing specific gestures you can open any bookmark, here's a quick tutorial. First of all, click on the properties on the bookmark you want to open. Then, click on edit gesture and then on "new gesture". You can select gesture type, but let's stay with the default one now. Click on recognize and perform the gesture you want. Remember that the system uses 8 directions, so try not to mimic handwriting. Drawing a "U" shape, or something similar is your best bet. You can see when you finish that the software recognizes the gesture. If you did a half-proper "U" you should get "DRD" as in down, right and then up. Choose where you want the bookmark to open, click "ok" three times and try it out. Performing the gesture should now open this bookmark.
Further editing
You can edit, and add any gesture in the same way as I described above. Experiment and try out different approaches, this could make you a lot more productive, taking the repetitive tasks away from browsing.
Download Mouse Gestures from the Mozilla addon page