We're using Akamai for XERQ's static assets and have noticed a 20% traffic drop today. After scratching our heads and remembering that Memorial day is next week

We're using Akamai for XERQ's static assets and have noticed a 20% traffic drop today. After scratching our heads and remembering that Memorial day is next week, it's a bit relieving to see this isn't just us. Can anyone recommend a monitoring tool that can check from many locations at the same time? We're using nagios and a few other homebrew solutions from 3 different datacenters, but none of them picked this up.