As far as I know there is no one doing that sort of service. There a number of broker sites where you can sell ad space but not sure of the results for an Indian audience site. You'll need a multi-tiered option:
- google ad sense
- premium priced spots from 2 - 3 online ad networks
- and individual sales to small businesses serving your industry (if they are online you can engage them via email, or else you will need to go down to their hadda and smoke hookahs with them to close the deal. :))
To manage all these without going insane while allowing you to scale up you'll need an ad server. Open X or something similar.
I have tried out Adsense and am looking forward to more on individual sales now. I guess going down to the adda is the best thing to do :)