My biggest concerns for any web site is that it:
is compatible with as many different platforms and browsers as possible
still looks good after users customize browser window, text size, and so on
is easy to use and simple enough to allow growth in scale without much pain
My web sites incorporate the use of:
hand-coded HTML
JavaScript and CSS (DHTML)
Photoshop (with ImageReady)
For larger-scale designs I would also employ the following if needed:
Flash and ActionScript
Acrobat (publishing PDFs)
Dreamweaver (or GoLive)