I write all my HTML in a simple text editor. This allows me to write 'clean' code that is very easy to understand if you open it in a text editor and displays very fast in a browser. As a result of having developed and continuing to maintain this site on in several different OSes, these text editors can vary from hour to hour. Fortunately ASCII stays the same (except for that CR+LF issue) no matter what OS you happen to be using :-) When I first started (sprint '99), I did all my image editing in Corel PhotoPaint 7. Since then, I have not had to do any further graphics verk so the Gimp has not come into play yet.
I do my primary development using Netscape Communicator/Navigator 4.x as a testing environment. However, I eventually test the site in every browser/OS combo at my disposal. The site is generally tested for compatability with the following browser/OS combos: