Is there a common lib between webapps, but not instances?

[Frank Diakovasilis]

I have multiple instance of Tomcat set up with multiple webapps in each.  I
would like a jar file to be shared across the webapps, but not across the
instances.  Is there a directory in place for that, or does anyone know how
to get around this?
TomcatHome\common\ is shared across instances so is not good.