I've used image maps in the past with big ass images, with pretty much no problems.  Today I got a message that one of our websites wasn't "live".  Initially confused, I went to the site and clicked on the links and they were working.

Now on the phone with the person, I asked what they were using.  They were using Safari, so I initially chalked it up to that.  Then I used MSIE and guess what, the links didn't work!

Sure enough after looking at the html (It's a simple page) and at an imagemap syntax example I was missing a pound sign (#) in my usemap attribute.  Firefox I guess "helped" me by making the site work, but it also gave me the false sense of that it was working for everyone.

Lesson I learned today: Give a quick test on even the most simple ass pages on a few different browsers.  You never know what might turn up.