The problem it solves is small but important, and this is now the third company at which I've solved it...so I'm sure there are more folks out there dealing with this same issue. ;)
Besides analytics, seems like this could help SaaS products that want to offer a trial or demo without ever creating an account up front–just spin up an account on the fly with the uid. If they actually signup, marge their real info.
I'll definitely be trying this out.
You definitely could use this for trial/demo accounts, too. You'd want to think carefully about abuse prevention, I suspect, but in the right circumstances it could be a really lightweight way to handle this.
Seems like it wouldn't be too terribly hard to add to nginx...hmm... ;)
http://sysadvent.blogspot.com/2013/12/day-5-gentle-introduct...
I actually think they're pretty different problems. WebServerUid is about uniquely identifying a single browser over hours, days, months, or years, while X-Trace is about tracking a single request over its (hopefully) single-second-at-most lifecycle -- but they're both really useful, and I'm glad you posted that link.
