Use Jabber to monitor the load average, and other system statistics, on your machines. (Requires python-jabberbot.)
Set jid and password in the config file as appropriate (you'll need to create the Jabber user, and subscribe to its presence, in advance), and run it on the machine that you want to monitor. It just sets the bot's status to the current load average, as reported by /proc/loadavg, the system uptime, as reported by /prog/loadavg, the memory usage, as reported by /proc/meminfo.
It will also show who's currently logged (according to /usr/bin/who) in when querried.
An old screenshot, showing just system load and uptime:
You can obtain the source code via git:
git clone http://vcs.uhoreg.ca/git/jabberbots.git/
systembot is in the public domain. Do whatever you want with it.