If you aren't passionate about the subject i wouldn't do an episode on it. Just go with what you are passionate about and the episode will be as good as the first one. Keep up the good work :)
I'm developing a social bookmarking product, but it's just a bit too early-stage to look at (it's called Favy)...
Meanwhile, I'm asked a lot about "social media marketing" - in other words using Web 2.0 tools to market products. So, how a company would best use Twitter and Pownce and widgets and social networking and so on to market their product/service. There are still a lot of people saying "put a page on facebook, slap a few videos on youtube", but we all know that's not really going to work very well.
So it would be great to hear your thoughts about spreading the word about a product and service (of any kind) through the Web 2.0 tools that you're passionate about. The twitter explanation was really good!