We used to do this on EQOA. (EQ for the PS2). Not everyone was able to get time cards for it but they were able to keep playing by purchasing time codes from other players. However, EQOA had a very small tightknit community and scammers were easy to spot and blacklist. Here, well I'm pretty new but it seems like you could get away with it easier.
You could trade the code from the time-card to someone in exchange for adena though... but seems to me its almost asking to get yourself scammed.
It's basically the method a lot of EVE Online players use to get game time financed in-game. Of course, EVE has "game time" as a valid form of currency, too. :)