The [[http://www.mozilla.org/projects/venkman/|Venkman]] !JavaScript debugger extension works perfectly in Conkeror. After installing it, you can start it in one of two ways.  From the command line:

{{{
conkeror -batch -venkman
}}}

Or, after enabling a glue-code module that comes with Conkeror, from a M-x prompt.  To enable the glue-code module, put the following in your rc:

{{{
require("venkman");
}}}

Then you can start Venkman with `M-x venkman`.