The Mac OS X Dock is Apple’s glory but normally it seems very good but if it Transparent then its seem awesome,it is quite simple make it and it can make transparent by 3rd party software like mod dock
To make the dock transparent in Lion / Mountain Lion type the following two
commands in a terminal :-
1:-“defaults write com.apple.dock hide-mirror -bool yes”
Then
“killall Dock”
It is like this
2:-“defaults write com.apple.dock hide-mirror -bool no”
Then
Restart your Macintosh / Hackintosh to see effect