Since I've been developing for mobile devices lately, I've needed to test what the site does based upon what browser is hitting it.
I've found a need to make my web browser report the User Agent from the Blazer browser or any other browser for that matter. There are quite a few ways to do this. Luckily a co-worker happened to show me the User Agent plug in for Firefox.
It's called User Agent Switcher and lets you switch out the reported user agent of your firefox browser at will. Remember, this of course does not emulate how the target emulation browser would render the page, but simply reports that you are using that particular browser to the server.
chrispederick.com/work/user-agent-switcher/
Here are a couple of sample user Agent strings I've found handy.
Treo 650 Palm
Mozilla/4.0 (compatible; MSIE 6.0; Windows 98; PalmSource/hspr-H102; Blazer/4.2) 16;320x320
Treo 700 Windows Mobile
Mozilla/4.0 (compatible; MSIE 4.01; Windows CE; PPC; 240x320)