I've been spending a lot of time recently messing with responsive design at work and in my personal time. If you haven't looked into it yet you really need to because it makes it MUCH easier to create mobile friendly websites.

I ran across a tool yesterday called Responsivator that allows you to quickly see what a page will look like for various screen widths and heights:

http://dfcb.github.com/Responsivator/

As an example I ran the getskeleton.com through the tool and got to see the results I normally have to resize my browser to see. I also ran my work site through it and it worked perfectly. One of the nice features to this tool is that it's just a collection of iframes so I was able to view the site while I was logged in.