If after following all the instructions in the Tomcat docs for enabling UTF-8 support (http://wiki.apache.org/tomcat/FAQ/CharacterEncoding#Q8) and you still run into UTF-8 issues, and your webapp involves reading and displaying the contents of files, give this a whirl.

In catalina.sh, either at the top of the file or after the long comments, insert this:

span class="st0">"$CATALINA_OPTS -Dfile.encoding=UTF-8"