I came to a conclusion today, I'm not sure if this sort-of-method has been discussed here (or anywhere) before: I'm getting 100+ spam comments on my major sites a day. Most of them are using keywords in their names, and of course the URL they want to rank. All I have to do is compile a nice list of keywords, load them up in a keyword research program and find some that are worth fighting for. This can be the first filter when you're looking for new niches and keywords... And it should be easy to rank for these, I mean, if they're spamming their sites directly then I'm sure some advanced SEO will shoot you to top ranks in no time. What do you think?