I'd consider these in some sense "essential" but you're likely to get a different answer depending on who you speak to:
* Non-web development: C++
* Web development: PHP
Both Pascal and Basic were designed as teaching languages, so they are as KISS says, great starting points. LISP is used mostly in academic contexts so I wouldn't recommend it for a beginner. C# and ASP are used by Windows programmers, C++ and PHP mostly by non-Windows programmers. So your choice of starting points may depend on the industry you want to work in.
If you might be interested in a career in software, a couple of phrases to keep in mind are object oriented programming and agile programming, both of which are hot right now. One of the hot areas of research in web programming right now is AJAX (note that OO programming, agile programming, and AJAX are all approaches or methodologies rather than programming languages in & of themselves). C++ is an object-oriented language which is why I recommend it (though you can do object oriented programming in any language, even LISP).