There's a nifty demo at Apparent Networks that's less like a demo of a performance management app and more like a way to understand how the dynamic, heterogeneous (disaster-prone, largely incompatible but somehow functional, anyway) Internet carries WAN traffic across the U.S.
It doesn't just tell you your bandwidth by round-tripping a ping to New York. It shows latency, jitter, percentage of packets dropped and a lot of other detail that would be partially useful if you were trying to pinpoint a network problem between, say, the Atlanta office and Salesforce.com. (Except it would just be the city of Atlanta and Salesforce, or Amazon's EC2 servers and Salesforce, or Newark and Rackspace. )
Upgrade a bit and the service will show you in nauseating detail what paths your packets take to the servers of specific service providers, where they are lured astray or dropped altogether, and where they just bunch up and wait a few microseconds so the VoIP and videoconferencing systems freeze up every few seconds and all the execs get pixilated or talk over each other.
It will also let you dazzle the LOB managers and the rest of the IT crew with the specificity of your information and analysis of the network paths imposed by your ISVs and backbone carriers, without really highlighting that the original problem, now erased, had more to do with the way you set up your routers and it was pointing them in a different direction that eliminated 2 hops, half the jitter and made the CFO look, if not dignified, at least not like an 8-bit video game from your childhood.
That kind of specificity only comes in the paid version, though; always a catch.
The paid version costs $100. Per month. Per location. Not per seat, or per application or per server. Per building.
Apparent puts in n appliance the size of a USB plug-in charger that gets a power supply and ethernet port. It tells Apparent's cloud-based service which physical locations you want to track, sends the metadata from those sites, and you get an almost-real-time detailed view of your packets flying cross-country in microseconds (probably more than you'd prefer).
There are other services, too. Some free, some not. This is the newest one, though, and has the most colors in its UI, so it must be the best.