Apart from embedding "?crid=0001" or similar in the Destination URL?

You can have a unique destination URL for each advert - but beware the lurking editorial review, of course!

I fully agree with Tom - it'd be really useful to have a supplement or supplements to the {keyword} substitution that carried, possibly:

* creative ID - very handy

* keyword ID - somewhat handy

* adgroup ID - useful

* campaign ID - less useful

* account ID - much less useful

* affiliate ID (for content search) - hard to derive in most analytics packages

* actual cost for this click -

* actual position for this impression - yay!