Two of the internet companies I most admire, Google and eBay, each celebrated birthdays this week. Google turned six. eBay turned nine.

Both companies have excelled because they took an innovative idea and proved its value. Google’s idea was a search algorithm that relied on link popularity rather than page content, and they followed that up with another innovation: an intelligent advertising network that leveraged the Google brand and the technical power of the Google network. eBay’s innovation was creating a single auction-based economy. They overcame the skepticism of internet and peer to peer sales and implemented a simple auction system that, combined with a critical mass of users, created a perfect market.

I’m not sure exactly what event these company equate to ‘birth’ (the idea? the site launch? the first transaction? the incorporation?), but I thought it was interesting that they both celebrate their origins during the same week. What is it about the first week of September that spawns innovation?