I will mention Tinyproxy in the hope that it helps someone. One of the features is that it can listen across multiple virtual interfaces and it will then connect with the remote site using the source IP from the interface you accessed it thru. It can be very useful in a situation such as this. It can be configured to be anonymous (no headers to betray you).
Client ----> Proxy 192.111.111.1 -> Your IP: 192.111.111.1 ---> Oron
Client ----> Proxy 192.111.111.2 -> Your IP: 192.111.111.2 ---> Oron
Client ----> Proxy 192.222.222.2 -> Your IP: 192.222.222.2 ---> Oron
etc.
http://en.wikipedia.org/wiki/Tinyproxy