Recently I had to aggregate the amount of 200, 400, 404, 500, 503, and 504 HTTP 1.1 Codes from all of our Nginx and Ruby On Rails systems. So I decided to write a quick plugin for Zenoss that all you need to do is pass the devices or Device Class you want to aggregate the data from and the DataPoint name.
Also this makes it simple to use the Zenoss Thresholds and create Aggregate Reports based on the datapoints you use with out having to do some fancy python coding… 
Enjoy
Example..
python AllenZenossAggregate.py -h Usage: AllenZenossAggregate.py -d "nginx-1" -d "nginx-2" -p "nginx_codes_count200" OK Aggregate for devices nginx-1 nginx-2 is 34|aggregate=34 AllenZenossAggregate.py -o "/Server/Linux/Nginx" -p "nginx_codes_count200" OK Aggregate for /Server/Linux/Nginx class is 22|aggregate=22 Options: -h, --help show this help message and exit -d DEVICE, --device=DEVICE The device you want to grab the datapoints from. -o ORGANIZER, --organizer=ORGANIZER The Class you want to get your list of devices from. -p DPOINTS, --dpoints=DPOINTS Name of DataPoint nginx_codes_count200