In case you haven't heard about it yet....
... Firefox 3 is available for download, with the intention to set the record for the most software downloaded in 24 hours.
The initial announcement was
Download Day is here!
Set a Guinness World Record
Enjoy a Better Web
Sounds like a good deal, right? All you have to do to help us set the record for the most software downloaded in 24 hours is get Firefox 3 now
it's that easy. We are not asking you to swallow a sword or to balance 30 spoons on your face, although that would be kind of awesome.
Please download Firefox 3 by 17:00 UTC on June 18, 2008. That's 10:00 a.m. in Mountain View, 1:00 p.m. in Toronto, 2:00 p.m. in Rio de Janeiro, 7:00 p.m. in Paris, Madrid, Berlin, Rome and Warsaw, 9:00 p.m. in Moscow, and June 19, 2008 at 1:00 a.m. in Beijing and 2:00 a.m. in Tokyo.
but now, I see the deadline slipped a bit by 1 hour and 16 minutes:

Waouw - days of 25 hours and 16 minutes - I want these :-)