On a shared hosting, HostSpy addon is a free useful tool to find out who current website's ip neighbors are.
The Host Spy extension displays the host name check results with ease.
Just right click on the current page and select Host Spy menu item, view other host names result in a new tab on hostspy.org's website.
* Auto resolves host names
* Shows results in a new tab on www.hostspy.org
* Other feature "Search By Ip" available on website