RemCom is RAT [Remote Administration Tool] that lets you execute processes on remote windows systems, copy files, process there output and stream it back. It allows execution of remote shell commands directly with full interactive console.
It is similar to psexec except it is open source.
Download RCE at http://sourceforge.net/projects/rce/
For more info, refer to http://talhatariq.wordpress.com/2006/04/14/the-open-source-psexec/