Live bookmarks are the same as RSS feeds. They're a useful feature of finding the latest news. Hardware Forums itself has an RSS feed feature. If you look at the right of the address bar you'll see a little icon next to the drop down box button. Go the the hardware forums home page, click this icon and choose where you want to store this live bookmark. I put it in the bookmarks menu, but you can have it on the bookmarks toolbar if you wish.
Once you've added an RSS feed, click it (or hovern over it if you saved it in the menu) and you'll see a list of the latest threads made in the forums. The live bookmarks will update themselves often, but you can manually update them by right clicking>reload.
As for extensions, my favourite one is mouse gestures where you can use functions like close tab, next tab, previous tab, back, forward, refresh. Go to the extensions website and search for mouse gestures. I have mine set so that an up,down gesture reloads the page etc.
