Search vs. Contextual Networks
I don't know if my experience is normal or not, but here are the statistics so far on my AdWords campaign using the keyword "venture capital".
Search - 8,416 impressions, 54 clickthroughs, CTR 0.6%, average CPC $1.11, total cost $59.71
Contextual - 66,960 impressions, 86 clickthroughs, CTR 0.1%, average CPC $1.11, total cost $95.33
that means the same keyword is 6 times more effective generating a clickthrough on a search than a contextually placed ad.
on the other hand, Google is able to run my ad 8 times more often on contextual placements than paid searches.
it seems to me that search is a lot more effective, but there's a lot more available inventory in the contextual networks.