This is my baby: www.cannedbanners.com. It’s a managed dynamic creative platform. Provides an abstract architecture for pulling in structured content (e.g., product feeds, APIs, etc), tracking/identifying audience members, and then at runtime, matching said content to said viewers according to an advertiser’s business rules.
So, being in “the biz“ myself, I’ve found a couple of your posts very interesting. :-)
Now you’ve got me thinking whether Predictive would be a fifth category of Signal. I suppose if an advertiser wanted a “latte OR Frappaccino” signal and you took a large unrelated data set and algorithmically mined it to generate your own signal, then you’ve created something that wasn’t there before. That the Predictive signal would be approximated wouldn’t disqualify it — all four signals I mentioned are approximated in some way.