Natsu no Arashi 09 poped at Youtube an hour ago, and my wish was granted in the first minute the of show:

No idea who the little freak with pantsu on his head is.

UPDATE: DiGiKerot has a more complete collection of cameos, which came quite thick. Note that SHAFT uses general cultural references quite a bit, e.g. Tenkousei in 08. It's completely impossible for me to catch them, unless they are stated explicitly like the 1936 movies that Arashi liked in (BTW, the year of King Kong). I still have no idea what the tank was about. Good money is on most of these flying right over my head.