Q: How best to populate a new site?

I've posted something similar on Reddit - but didn't get very far (most of the responses degenerated into a joke, but that's probably because my example was about a dating site)

And, I saw a similar post here on HN which leads to the OP's blog at http://startupblog.wordpress.com/2009/09/04/inventing-demand/ - but I think that works only for places that do actually trade physical goods, like eBay or any store-like sites.

Anyway, I'm hoping I'd get more thoughtful insights here.

So the question:

How best to populate a new site? sites that don't actually trade goods? (or simply trade on virtual goods)

To put in context, think: - craigslist - reddit - personals/dating - music/book/reviews

Some suggested scraping existing content from similar sites to create the initial population (creating dummy user accounts) - but that seems icky. And, likely not tenable in the long-run - actual early users will detect/notice scraped articles.

Using/asking friends and colleagues might not be as effective (eg: not having enough good writer friends, or willing to participate in a dating site)

I think, there are also services out there that offer to populate your site (like this: http://www.evercurrent.com/adding_profiles.html) but again, new members will likely try to connect with the dummy accounts and not get a response, so will not come back or deem your site useful.