Take a look at JPivot that is used by Pentaho Mondrian.
JPivot is an open source Java tag library for connecting to cubes exposed through Mondrian (Java OLAP server) or through XML/A (which I believe is used by Microsoft Analysis Services).
The JPivot control is pretty comprehensive although it could do with a little bit of a facelift. I believe that a new project Pentaho Analysis Tool (PAT) is in development as a replacement for JPivot this uses GWT to render a nicer looking UI (http://wiki.pentaho.com/display/COM/Pentaho+Analysis+Tool).
I use Pentaho Mondrian along with JPivot to present my multidimensional data on my intranet. I am using a ROLAP schema running on SQL Server 2000. It works ok and also supports generating charts with JFreechart.
Mondrian Java OLAP Server - http://mondrian.pentaho.org/
JPivot http://jpivot.sourceforge.net/ - Screenshots http://jpivot.sourceforge.net/temp-N101F1.html
It may also be worth looking at Eclipse BIRT I beleive that this possibly supports a sort of crosstab control but i've never tried it.