There really aren't any. Any attempts to formulate some +200/-100 rule is murky at best.
There is some, albeit poor correlation that high online ratings indicate a comparable rating strength (only for live chess at slow time controls!) if said person were to be playing on the USCF.
Though the reverse direction seems to be a bit more promising. A strong USCF player tends to perform just as well at live chess at SLOW time controls on usually any chess server.
Trying to compare the ratings of some XYZ Chess server's One-move-a-day-chess (Online chess) or blitz/bullet/anything-but-slow to USCF tournament play seems like a waste of time.
In general, how do online ratings compare to USCF ratings? I realize that there is no set rule, I am just looking for any general guidlines