i want a "mylist", not craig's list

so here's a thought. my best man christian is coming to new york next weekend, and is finding it impossible to find anywhere decent to stay for less than $400/night. i have loads of friends in the city who'd probably be willing to put him up for free, or for less than $400/night, given that i can vouch for him. but i can't really spam them all with an email for this, and then something else in a few weeks. he's surfing on craigslist to try and find places, but neither party then has any independent reputation. 

why not merge craigs list with my contacts book, and add in a publish and subscribe element. so that way i can subscribe to topics that i might be interested, and know who the people are - as my  friends, or friends of friends. obviously this is the kind of thing that social networks could enable but i) none of them are comprehensive enough to include all the people in my contacts book ii) doesn't have good integration with  contacts books and ii) doesn't have a publish-subscribe element apart from the status update, which is rather a blunt instrument.  

we need a way of brokering interesting connections between people based on their collective set of interests that delivers a marketplace with enough liquidity (ie most people participate),  but also keeps  privacy and spam at bay.  another thing for the boffins to work on.