1. You have an Apache webserver with a Content Handler registered at the location "/users"
2. You find a user via http://junk.com/users/stevej?mode=full
3. the first character of /stevej?mode=full is ripped off, and you now have the username sittting on top of your stack until the '? and the rest of the string is easily parsable.

We've hereby completely bypassed the use of any regexes to determine where a user request should be routed to. viola.