When a User of an application (e.g. siebel, wordpress, salesforce.com) sees an error popping up on his/her browser, that error is captured and can be viewed on many of the Germain APM dashboard (and that has been available over 2 years now, yet some customers were unaware of it).

Example

"The server you are trying to access is either busy or experiencing difficulties. Please close the Web browser, open a new browser window, and try logging in"

Where you can see

"Extra Info" tooltip or field available on many Drill-through and RCA dashboards