Chrome: Sometimes, you don't really need to open a new tab when you want to check out a link; you just want to get a quick look at where the link goes. Intab is an extension that essentially adds a "quick look" option to those links you find.
To activate Intab, just hover over a link and hit Windows+Alt (Option+Command on Mac) and left-click. The link will open up inside the tab you're on as a resizeable panel. It's a simple way to view two pages side-by-side without opening yet another tab. Intab is in beta, so you might notice a few quirks, but it worked well for us. Firefox users might want to check out Tile Tabs for a similar experience.
Intab [Chrome Web Store]