High value ads for small, high value audiences

Can anyone recommend anyone?  I am currently looking at adding an advertising capability into a range of high value vertical web properties for professional communities. I am not looking for commodity ads as the user community is professional,and the ads served must also relect on the brand values of the publisher and the audience. We are working with a number of B2B publishers - For an example of our work please look at the attached article from The Sunday Times and follow the enclosed link to SearchMedica – a vertical professional online community serving 55,000 UK GP’s.  http://www.timesonline.co.uk/article/0,,2095-2415420.html