We use UTM codes to track campaigns. Since we use UTM codes, we can use Google's URL builder. We have set up our classification rules to recognize the 5 primary UTM types such as umm_source, etc.

We used to use a colon, but recently switched to a pipe. We had too many instances where an author would use a colon for something else, such as a subject line and screw up our tracking. We haven't seen errant pipes...yet.