The simplest method used to bypass proxy blacklist filter (implemented for example on proxy squid) is to use Google Translate service which can simply become a web proxy. Let's see how this can be done:
suppose that you would like to go to ivanobinetti.com web site which is blocked by proxy blacklist. You only have to go to:
translate.google.com/translate?u=http://www.ivanobinetti.com
suppose that you would like to go to ivanobinetti.com web site which is blocked by proxy blacklist. You only have to go to:
translate.google.com/translate?u=http://www.ivanobinetti.com
Be careful to select a destination language (that one in which you want to translate) different than original language. For example, if you have a english site you can select italian as destination language and, in general, you can select any language except english (which is original language).
Enjoy your new and always available web proxy.