If you’re looking for professional looking (non-free) templates, look no further than:
I just signed up with their template club. It’s great. You can download all of their themes, and you get the base Fireworks PNG files, as well as tutorials on how to customise their themes.
Here are some of the ones I like:
Another place that I saw some nice templates was http://www.pixelsparadise.com/I liked this one from pixelsparadise, but it costs 25 Euros – and I have no use for it at the moment: