headshot over on rs6 international has an excellent sticky for installing some nice looking vents similar in style to the SL 65 AMG vents.
http://www2.rs6.com/forum/showthread.php?t=17474
Look pretty subtle and the installation has design features to keep the rain out from under the bonnet (hood to our over the pond colleagues).
I am tossing up whether to install the headshot style vent or louvres like on an e type jaguar I have- the original cool louvre style.
Only problem is on the e type, when it is raining cats and dogs and you stop suddenly you get a nice plume of steam as the rain sloshes off the bonnet through the louvres onto the hot exhaust manifolds.
The water under the bonnet doesn't affect the e type electrics as they are taken care of by Lucas "the inventor of darkness", but I dont really want to try the effect of dumping water into the under bonnet electronics of the RS6 to see what happens.