This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Excluding a URL for a filter, i believe is not possible. You will have to include all other possible URL patterns. Or one cheeky approach would be include /* for your filter and to code another dummy filter (that does nothing) and map /s/* to it.