Signing Text from JavaScript
http://docs.sun.com/source/816-6152-10/sgntxt.htm
SecClab PKI Utilities
http://secclab.mozdev.org/
Secclab is a XPCOM Component that implements some PKI functions. Secclab is open source and dually-licensed under the GNU General Public License and the Mozilla Public License. You can download and install Secclab from the Installation page.
Features:
-Sign/verify CMS detached Signatures from XUL applications
-Encrypt/Decrypt CMS encrypted messages from XUL applications
-CLABSignString, a cryptoSignText clone that enables in mozilla (and phoenix) form-sign feature.