Data mining query logs? Then these research papers might interest you.

Ji-Rong Wen, Jian-Yun and Hong-Jiang Zhang:
Query Clustering using User Logs ACM Transactions on Information Systems (ACM TOIS), 20(1), 59-81, January, 2002
http://doi.acm.org/10.1145/503104.503108
Hang Cui, Ji-Rong Wen, Jian-Yun Nie and Wei-Ying Ma:

Query Expansion by Mining User Logs

IEEE Transaction on Knowledge and Data Engineering, Vol. 15, No. 4, July/August 2003.

http://csdl.computer.org/comp/trans/tk/2003/04/k4toc.html

or

http://research.microsoft.com/asia/dload_files/group/mediasearching/2002p/QE-TKDE.pdf

 

Gui-Rong Xue, Hua-Jun Zeng, Zheng Chen, Wei-Ying Ma, Hong-Jiang Zhang, Chao-Jun Lu:

Implicit Link Analysis for Small Web Search

SIGIR Conference, 2003.

http://research.microsoft.com/~i-hjzeng/p31261-xue.pdf