This module allows for integration of Drupal with NGP Software's Campaign Office Online and Contribution Web Package. This will allow you to take email and volunteer signups and contributions directly through your web site. Some other modules also integrate with this to provide additional data capture points including Forward, Petition, and Letters.
This module requires NuSOAP. You can download NuSOAP here and extract the zip file into sites/all/libraries/nusoap (the lib folder in the zip should end up as a subdirectory in nusoap). Alternatively, if you have shell access you can run this command from within the sites/all/libraries directory:
cvs -d:pserver:email@example.com:/cvsroot/nusoap co -P -d nusoap/lib lib;