I listen to This Week in Startups and Jason Calacanis always makes the ads really personal. I've gotten value from at least a couple products advertised on This Week in Startups and This Week in Venture Capital (e.g. Scott Walker, startup lawyer).

Many of the comedy podcasts I listen to aren't in love with the products like many of the tech podcast hosts, but they often deliver the ads in a funny way. I think it's very unobtrusive most of the time (and seemingly effective).