X-Cycle for Chrome
More About X-Cycle
Configure a Target IP address or Hostname, and a List of IP addresses.
This extension will pick one IP address from the list and insert it into requests to the target server as the value of the X-Forwarded-For header.
This is geared towards testers of Web Application Firewalls, where you need to generate traffic that looks like it's coming from different IP addresses. Normally, servers do not trust XFF that is not set by their DMZ, so you will need to configure your WAF to accept untrusted XFF first. I found it particularly useful in Testing F5's Application Security Manager Software.
* bug fixes.