lucy24 - 7:33 am on Feb 6, 2012 (gmt 0)
The ability to specify any user-agent is built in to my (mainstream) browser.
I think they all have it, though some are easier to find than others. (I detoured here to look.) Safari is definitely the most straightforward. Others you have to dig around in extensions.
But if you're pretending to be a robot, you can't complain if you're treated like one ;)