Monitoring /proc/user_beancounters to see if any VEs are hitting limits is an important part of managing an OpenVZ installation. VEs that are hitting key limits can have applications malfunction in strange ways that can only be diagnosed by realising that it is a UBC configuration issue.
This script, when run periodically (using cron) will detect changes in the failcnt field of /proc/user_beancounters
failcnt.py http://img.cs.montana.edu/linux/openvz/failcnt.py