I came across closure today. It's an X-based web browser written in common lisp.
Not sure what to make of it. It looks like it hasn't been updated since 1999, and was more a proof of concept than an attempt to build a full, modern browser entirely out of Lisp code (modulo Xlib).
More than anything else, it looks like proof for the axiom that any language is "weak" until it has been used to create a web browser. (There was a neat Tcl hack that was a very small web browser in the mid-90s: it used a single regex to convert HTML to Tk drawing commands, and eval'ed the result. At the time, it rendered lots of pages faithfully and much more quickly than IE or Netscape...)
