There is one area where Zabbix is way behind commercial competitors and that is the field of reporting and statistics. Today there is no easy way of getting good statistics or reports from Zabbix. Please see the quote below that was taken from this thread:
http://www.zabbix.com/forum/showthread.php?p=59925#post59925

"Say for example that I want to know which 10 servers that had the highest decrease of free space, highest avg CPU load etc.. for the last 30 days. This can't be done in zabbix today.

I know that I can create a report based on triggers so that I get a list of the trigger status in % for each host. But this requires a trigger for the information that I want and I can't sort the list in any way, so this is kind of lame actually.
What I want is a specific screen where I can create all kinds of reports and statistics for the last month. Some things that I want:
A list of the top 10 servers that has had the highest average CPU load (or any other monitored item) for the last month.
I want to be able to get a list of all monitored servers and get the total disk space, current free diskspace and the change of free disk space for the last month (SORTABLE by category). I want to be able to make similar comparisons for any monitored items and host.

Something like the Overview screen in the monitoring section, BUT containing monthly or weekly averages and of course the most important; it has to be sortable by category (ie. highest CPU load in a decending order...)."

What you probably need to do is to make available the creation of reports based on actual data insted of the current "Trigger=True or False" approach. Its just not versatile enough, unless you're gonna have hundreds of triggers for each Item that you're monitoring. Please also make all the reports exportable, see my other feature request on that.