Infrastructure for Digital Language Resources and Tools
Wmatrix is a software tool for corpus analysis and comparison. It provides a web interface to the USAS and CLAWS corpus annotation tools, and standard corpus linguistic functions.
http://ucrel.lancs.ac.uk/wmatrix/ (and a direct link for registered users: http://ucrel.lancs.ac.uk/wmatrix3.html)
A free one-month trial is available.