Hi fransgaard,
I guess you can use any design program you want to web design, I use illustrator and photoshop but i don't see why you can't use indesign, after all it's easy to rasterize an indesign file into photoshop and splice it's elements up. I guess as many web designers are on PC and haven't got indesign would be the only reason i can think of! Cheers Matt.

http://www.design-intellect.co.uk

ID's tools are built explicitly with print in mind and meant to emulate the feel and workflow of traditional print design; as a well-designed app, it does not waste much time on features that don't fit into that intent. For web design Fireworks delivers web-oriented tools that you won't find in other applications (for instance the way it handles design elements as separate objects, the Pages tool in CS4, or the PNG8-alpha export that you won't find in any other major design app). Photoshop pulls a distant 2nd, and I still switch into it and Illustrator when I need to build something to bring into a Fireworks layout. They all come in the Adobe master collection and Design Premium collection though, so I don't see why someone would use a sub-optimal tool that wasn't intended for the purpose of web design when you get them all in the same pack. I'm not incredibly experienced with inDesign, mind you; the only time I use it is when working with print designers who use it. Maybe someone who has used it more extensively can give a detailed breakdown.

Oh @waveslaves: InDesign is in the master collection and the design premium package at least in CS3 + CS4 for both PC and Mac. Note that the newer CS versions are *not* backward compatible with earlier ID documents which is a huge pain in the ass.