I have a personal (digital) Rolodex of over 10k people as I've been in various sectors of life: politics, business, non-profits etc. Some of these folks fall into multiple categories: I want to solicit them for fundraising for politics or perhaps a local do-gooder non-profit, others I'd like to do direct sales via my custom clothing or personal training business. 

While there are custom fields in PD, I dont see where I can add multiple tags to contacts so then I can filter and tailor a (email) marketing campaign directly without overshooting to uninterested parties.