Aww come on Joe! Perl and Python are like... Well, OK, so not every page is using it I guess that's a point to consider. But either way, if you're going to become ANY kind of good Web Service person, at least an understanding of Perl and Python would be of great help considering that the servers the pages will run on is going to probably be using at least one of those for something.

I also have Python for Windows, and Perl. I find them useful in a lot of stuff, especially when Java Script isn't going to work for something. Like, if you need a certain thing to work a certain way and Java Script is not working out, Python or Perl will probably be able to handle it.

I also agree on PHP which seems required these days heh.

When I set up a web server for friends and people I knew to use for things, I used Vim to write the HTML, and then I tested it in these browsers to make sure everything was compatible:

Internet Explorer on Windows
Firefox on Windows
Firefox on Linux
Firefox on FreeBSD
Epiphany on Linux and BSD
Links
Lynx
Elinks
Konqueror
Seamonkey
Netscape
Opera

After that I knew it would work well. Like I said though, the HTML was done by hand in Vi. I did have a little JavaScript at one point.