If one umbrella is suitable for keeping one person dry from the rain, then it follows that a huge array of umbrellas should be enough to keep a whole party dry from the rain, right? That's just what Unsolicited Studio and DUS Architects did for a drizzly street party in Rotterdam.
They ended up combining dozens of umbrellas into a buckyball-like structure, large enough to keep everyone nice and dry underneath. It ended up looking really cool, too. Heck, this is something I wouldn't mind having available on a deck or balcony when it rains out. Of course, you always run the risk of all of them blowing inside-out at once, which would be a pretty serious pain.