I watched that Mixergy video too, and was inspired to try something similar :)

BSA is great, but if you need more inventory, you can get this strategy working on Google AdWords, too. You just need to create a new ad group, and use "managed placements" to specify the sites you want to target.

Since you probably don't want 100 ad groups, you have to get a bit more generic with your ads, but there are plenty of ways to do that and still get the "this is useful information, not some off-topic ad" effect.

Here's another tip: Once you have an ad that exceeds about 0.2% CTR, you'll often get much lower cost-per-click by switching the campaign to CPM bidding.

For example, if you're bidding $1 CPM, and getting a 2% CTR, your effective CPC is only $0.05! In CPC mode, you'd often have to bid $0.30 CPC just to show up.