Stole this from http://www.notblog.com/blog/ -- Forgive me Dave

simple way around internet policy
posted by dave

I know that a large number of my readers are stuck behind oppressive firewalls, often simply because the staff that runs the firewall aren't completely sure how to administer them. If the firewall is preventing you from accessing a site that you need for work, I would suggest this:
1) Start by pasting http://www.google.com/search?q=cache: into your browser address bar.

2) Paste or type the address of the site you wish to view, without the http:// part on the front. For example: http://www.google.com/search?q=cache:www.digikey.com

3) If you don't want to leave as many traces, paste &hl=en&lr=&strip=1 onto the end of the whole thing you just put into the address bar. That will remove images, thus preventing your browser from making a lot of image requests to the original site. Example: http://64.233.187.104/search?q=cache:www.digikey.com&hl=en&lr=&strip=1

Keep in mind that google only caches text, not images. This means that if the site is blocked by your workplace's policy, then you will still not see the site's associated imagery. This method will at least let you read text and will often give you the links you need to be able to download a document or image.
The other caveat is that you must form the URL for each new page that you wish to view via the google cache yourself, since clicking links within the google cache will take you to the actual site, not the new page's google cache.
This would actually be a good plugin for firefox... One that mangles all URLs into googlecache URLs...
Anyway, Enjoy!