Some handy web browsing time-saver tips
Open a link in a background tab by clicking your mousewheel. When you’re browsing blogs, news, Twitter, or Facebook you come across links you want to check out, but you don’t want to stop reading your current page. If your mouse has a wheel on it, click links of interest with the mousewheel to open links in background tabs as you read down a page, so you can switch to them later without interrupting your flow now. An extra tip for mousewheelers: Close background tabs in one click of the mousewheel without switching to them first, too.
Automatically restore the last tabs and windows you had open. Instead of loading a static set of tabs that don’t change when you start your browser, automatically load what you were looking at when you quit your browser last time. In Firefox’s Options dialog (get to it from the Tools menu), next to "When Firefox starts," choose "Show my windows and tabs from last time" to restore your previous browsing session. In Chrome’s options, on the Basics tab, select "Reopen the pages that were open last."
Regarding the tip to "Sync your bookmarks across browsers and computers" using "Xmarks" plugin, I suggest using Delicious.com or similar tag-based bookmarking service instead, either via the Delicious plugin or via the bookmarklet they provide (just drag-drop it to the browser’s "Links" toolbar that you can show from browser’s View settings). I use delicious and I’m very happy with it.