I'll re-edit this later when I have it fully put together, but here's the raw deal- 

Juniper EX series switches currently only support sFlow for packet/flow tracking/accounting. I want the same functionality I used to have in my old Riverstones (flow-based routers) where I could look up the active flows in the box and determine a culprit in a problem situation. So how to do this?

Right now I'll just include the diagram- basically you mirror traffic to a collecting server that converts the mirrored traffic to flows.

Right now I've got softlowd and flowd installed on an OpenBSD server and it's working great. Will update when I install Webview NR (or equivalent).