I was at a meeting with an agency earlier and we got talking about tracking conversions across multiple clients in unrelated categories. This could be useful for  a number of reasons, both to provide insight into the relationship between brands and also to enable targeting in future. Currently companies wanting to do this would need to either take a feed from DoubleClick or Atlas in order to use their user ids or actually share personal data between clients (which is unlikely to be possible for legal reasons). The new version of TagMan actually logs the global user id for all conversions, making such analysis easy. 

What’s more you can also get arrival data to tell you that the person who searched for car insurance and didn’t convert is the same person who’s bought a holiday from another client. The uses for this anonymous data are endless and will allow large agencies to use their scale to really add value for clients. And for those who want to go a step further you can also get TagMan to write its global user id into other peoples tags, allowing this data to be merged with other third party data or integrating with insight from your analytics system.