I have always wondered what open source tools are out there for web design just in case I decide to boycott Adobe or Adobe goes bankrupt or something. It turns out there are some pretty good options for web design. None of them are quite as good as Fireworks or Dreamweaver, but they do get pretty close at least for the classic Apache, MySQL, PHP setup.
Last, but not least we have the GIMP. It is by far the most popular open source image editing application. It lacks many of the features of Photoshop, but most can be accomplished using either plug-ins or a combination of steps. Exporting images using slicing is much more difficult than using Fireworks, but it can still be done.
Using open source software would not be my first choice, but if something happened where I did not have access to Adobe products I would still be able to be productive.