1. xhtmlgen
    xhtmlgen is an XHTML generator
  2. XHTMΛ
    XHTMΛ is yet another (X)HTML/XML manipulation library You can find it at common-lisp.net/project/xhtmlambda
  3. xindy
    xindy is an index processor that can be used to generate book-like indexes for arbitrary document preparation systems
  4. XIT
    A graphics toolkit from the University of Stuttgart which provides an object-based interface to the X11 window system, based on CLX and CLUE
  5. XL-Wiki
    XL-Wiki is a fork of CL-Wiki that aims to allow applications to modify and extend its functionality in interesting ways
  6. xlunit
    XLUnit is a Test Framework based on XPTest and JUnit
  7. XML
    The eXtensible Markup Language
  8. xml-emitter
    Often, programs have to generate XML output
  9. xml-mop
    Allows representing parts of XML documents as CLOS objects
  10. xml-psychiatrist
    xml-psychiatrist is an XML sanity checking/validation library written entirely in Common Lisp