Stumble it! 
Dopplr, the “social networking” site used by frequent travelers, was recently funded by a wide range of superstar investors (read: Martin Varsavsky (FON), Reid Hoffman (LinkedIn, PayPal), Saul Klein (Index Ventures, The Accelerator Group - Stardoll, Joost, Last.fm) and so on).
I frequently used Dopplr when I was in Europe due to all the traveling but hardly use it these days. Dopplr’s blog did not mention the amount they received. They’re still invite-only but ping me if you’d like one.
“We’re gratified that so many world travellers have already found value in Dopplr,” said Lisa Sounio, CEO of Dopplr. “Having this international group of active Dopplr users now joining us as strategic investors is tremendously exciting. Martin, Saul, Joichi and Reid have a great sense of business, technology, design and travel.”
Moral of the story: If a potential group of investors is already using your service with(out) you knowing it, life is set. This service will never be a global hit, but may be able to sustain itself due to the very fact that there are some people who are internet savvy and travel alot.
