The View Selection Source functionality known from Firefox
View Selection Source as you know it from Firefox with syntax highlighting.
The source code view has syntax highlighting -- you can even choose between two color schemes (see the Options page). In the window with the selection source, the same text as you have highlighted is selected. Also, you can hit enter to toggle word wrap.
There is also a bookmarklet version available:
If you happen to be an Opera user too, check out this version: