I have known this for a while now, but I didn’t think of submitting it here before.
So, if you want to change the look of your Dock (eg. I think, in the default dock it isn’t very clear to see when an application is open or not) you have to change some files you can find at /System/Library/CoreServices/Dock.app (ctrl-click show package contents) /Contents/Resources there you can find the images that represent the indicators (indicator_… files), dock background (scurve-… files), etc. when you replaced this files you have to restart the dock by opening terminal and type ‘killall Dock’you can find a lot of premade Docks on the internet (just google for it) my favorite site is http://leoparddocks.net/ I found the tip at http://macthemes2.net/forum/viewtopic.php?id=16782319
* note from James. I think we’ve covered this before, however I’ll publish this anyway as a re-cap! also be warned that you could ruin your dock by playing with these files
