A lot of recent tools really make development of web pages easier. The ones that motivate this entry are the bookmarklets pointed out by Ovidiu. Very cool stuff, especially the CSS test that allows live editing of a page's CSS ! It's best used with Ancestor which shows the CSS path of the element under the mouse. No excuse not to use all the fancy CSS features.

Other very usefull tools include LiveHTTPHeaders for Mozilla and the awesome HTMLArea that I use to write this entry thanks to Steven.

Life is cool with cool tools. Of course, I don't forget my beloved Cocoon for everything server-side !