Server Monitor Widget allows you to monitor any server running PHPsysinfo (http://phpsysinfo.sourceforge.net/). PHPsysinfo is very easy to install and is free!
Last comment from Widget Realm was that the multiple server functionality would be added "shortly" ... that was in July. Given the fact that the current version 1.2 was released in March I would consider this being dead. What a pity, it really would become a useful widget if multiplie servers would be supported.