LXadmin "Host in a box" is the only control panel that makes use of Lighttpd and DJBDNS which only uses 8 MB of RAM with a freshly installed system. The control panel itself uses 1 MB of RAM when idle. LXadmin "Host in a box" is part of LXadmin, the leading light-weight control panel in the industry. The only difference between the two is the use of different daemons.
This lightweight control panel has all of the features included in all leading control panels such as mail, spam filter, PHP, CGI, Perl, SUexec, FTP, MySQL and much much more. http://doc.lxlabs.com/lxadmin/client/index.html