How did you go about seeding your web crawler with URLs to crawl?
It's a directed search so it doesn't seem to need a particularly solid seed to get decent results.
When I did some crawler experimenting in my younger years, I thought I was pretty clever using sites that would let you perform a random Google searches. I would just crawl all the pages from the results returned.
Your method would undoubtedly be more interesting I think. It would certainly lead to interesting performance problems quicker, I bet.