I made a really simple tool that let's you lookup the DNS, WhoIs and IP of the site that you're visiting. It also let's you highlight IPs on websites, right-click and do lookups in context windows as well.

Hope it helps out other devs as much as it helps me on a daily basis:

https://chromewebstore.google.com/detail/ipaddressto-lookup/...

https://addons.mozilla.org/en-US/firefox/addon/ipaddress-to-...

The extension uses https://ipaddress.to