Hi I think its important to cover whats different about Haskell. Things like laziness are cool, but are harder to convince a strict programmer that they are useful. Types however are obviously very handy, if you can focus on why a Haskell program is so obviously correct easily.
1) the type system is a great aid to the programmer and programs are short. Therefore Haskell is very well suited for the independent developer who can't afford huge amounts of code. Open Source has many of those.
I'd also at least demonstrate Hoogle, but perhaps I'm biased :-)
2) polymorphism is also a great advantage. You can write your program in the most general types using e.g. only equality and order, and fine tune them later to more specific types which perform better.
I'd also focus on the fact that polymorphism can be inferred, in things like C++/Ada using polymorphism means littering the code with hints about the polymorphism. Thanks Neil