Re:hah (Score 1)

Passive:

pro - Tags are extremely small, readers are cheap, tags are cheap
con - Range, non-existant

I wouldn't say that the range on passive tags is non-existant. For example, UHF tags (EPC Class 1 Generation 2), which are currently the most used tag type in industrial applications, have a maximum read range of about 7 meters (20 feet). In practice, however, the range is about half that in order to achieve acceptable reading accuracy. Another thing to take into account with UHF frequencies is that some materials (such as liquids) will block the reading of tags.

Tracking people with UHF tags is also possible.