Here are some basic munin plugins for snort using perfmon,
done for: http://www.snort.org/reg-bin/forums.cgi?forum_id=1&topic_id=6758

Drop Rate:
http://download.gamelinux.org/snort/snort_drop_rate

Pattern Matching:
http://download.gamelinux.org/snort/snort_pattern_match

Traffic speed:
http://download.gamelinux.org/snort/snort_traffic

Alerts:
http://download.gamelinux.org/snort/snort_alerts

Avg KBytes/pkt:
http://download.gamelinux.org/snort/snort_bytes_pkt

Avg Pkts/sec:
http://download.gamelinux.org/snort/snort_pkts