I’ve surprised myself by starting to enjoy doing browser-side development in CSS and JavaScript more than I enjoy the server side. Prototype, Scriptaculous, LowPro, and a comfortably growing in-house library have gone a long way towards helping with this shift, along with finally getting down into the guts of CSS and learning about the box model. Tools like FireBug and the Web Developer Toolbar for Firefox have helped out tremendously, as well as native Mac OS X tools like XyleScope and direct linking to the CSS specs from within TextMate (very helpful when wanting to learn the real details about any given property).