XPath engines for Java

I'm working on the XPath chapter of Processing XML with Java,
http://www.cafeconleche.org/books/xmljava/

So far the chapter covers Saxon, Xalan-J, Jaxen, and DOM 3 XPath. Does
anyone know of any other XPath processors I should look at? I looked at
jd.xslt, but it doesn't appear to be set up to be used for pure XPath
search, as opposed to XSLT transforms. (XSLT will be covered in the next
chapter, mostly via TrAX.) Oracle seems to offer even less access to its
XPath internals. Can anyone think of any other XPath engines for Java I
should check out? Thanks.

--
+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo@xxxxxxxxxxxxxxx | Writer/Programmer |
+-----------------------+------------------------+-------------------+
|           The XML Bible, 2nd Edition (IDG Books, 2001)             |
|             http://www.cafeconleche.org/books/bible2/              |
|   http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/   |
+----------------------------------+---------------------------------+
|  Read Cafe au Lait for Java News:   http://www.cafeaulait.org/     |
|  Read Cafe con Leche for XML News:  http://www.cafeconleche.org/   |
+----------------------------------+---------------------------------+