As you already know the Hitchhikers guide trailer does a clever deconstruction of the Movie trailer (see post dated Monday, 25 June 2007). Have a look at these 2 trailers. Enjoy them but remember to watch them a few times and make notes about the 'conventions' and language structures typical of the genre.
DW
Click on the title 'Parody of the trailer 'voiceover' for a wikipedia link to Trailers.