Is there a way to get per-ip traffic stats from PF on OpenBSD 4.9? pfctl can give me the total traffic (bytes) for a given label, and pfstats for a given interface, and pftop can give me a "live" view of traffic, but I'm looking for a historical view- i.e. something I can look at and say "yesterday this IP used x bytes"
You can do this through a slightly convoluted (but very easy to manage long-term, and pretty well-understood) adaptation of Netflow traffic monitoring (using OpenBSD's pflow support).
Basically export netflow data for all your traffic, grab it with Flow-Tools, and feed it to something like JKFlow to parse (and graph/report on). There are also many other NetFlow crunching/graphing programs, and a number of real-time monitoring systems available.
You may also be able to magic something up using MRTG, but I'm not as familiar with that.