HTML/CSS - I started making sites around 1998 - 1999. Iv'e never been much of a designer though.
ASP (VBScript) - Worked with between 1999 - 2002.
Python - I switched from Windows to Linux and Python looked interesting. 2002
PHP - Getting back into web development. 2004
There are of course other languages which I've used. Bash I use on a daily basis and have done since I started using Linux, and I've played with my fair share of Perl.
I've been using PHP for a long while now and really am starting to look for alternatives (even though I'm employed mostly as a PHP developer). I'm not really that interested in web development either these days, which is OK, we don't make web sites (as such) where I work.
I'm thinking Ruby is looking like a prime candidate for good use. Been playing around with it for probably the last 12 months, and in the last few months looking at Rails. Node.js is also pretty interesting.