I had a few requests for these munin plugins after some discussion on one of the Asterisk lists and thought people might like them.
There are four scripts (three of which are based on a script by Paul McCormack.
Basically you just add them the same way as normal munin plugins.
By the way, if you're using Debian, installing munin is as simple as apt-get install munin and apt-get install munin-node.
So, the plugins:
This plugin displays concurrent Asterisk channels.
This plugin shows IAX peers (online/offline/unmonitored online/offline)
This plugin shows SIP peers (online/offline/unmonitored online/offline)
This one connects to the MySQL CDR database and shows how things have been over the last hour (number of calls answered, not answered, busy, congested).
You'll need to set your CDR database/table and the MySQL connection details in this one.
Let me know if you have any questions.