Open Chrome tabs can eat up a lot of RAM, even when not in use. TabMemFree unloads tabs after a specific amount of time to free up memory when you aren't using them.
If, like many of us, you keep tabs open in your browser because you want to check on them later, TabMemFree is a good way to keep them from taking up all your computer's resources. Just install it, give it a timeout value (like 15 minutes), and it will unload any tabs that have been inactive for that amount of time.
Unfortunately, the extension is a little hacky, which means it isn't perfect. When you unload tabs, you can't see what they used to be, they just have the extension's icon on them. Furthermore, since it unloads them, you'll lose any media playing in those tabs (like if you use Google Music) or any form-filled text you've entered. We'd like to see an option to ignore tabs from a specific domain, but hopefully the developer continues to add to the extension.