We describe the participation of the University of Amsterdam's Intelligent Systems Lab in the web track at TREC 2009. We participated in the adhoc and diversity task. We find that spam is an important issue in the ad hoc task and that Wikipedia-based heuristic optimization approaches help to boost the retrieval performance, which is assumed to potentially reduce spam in the top ranked results. As for the diversity task, we explored different methods. Clustering and a topic model-based approach have a similar performance and both are relatively better than a query log based approach.