I've mentioned I play for PLEX - so I thought I should say for the newbies/non-EVE gamers, what exactly is PLEX?
PLEX stands for Player License EXtension - it's an in-game item which can be bought with real money from CCP, traded in game, then cashed in for 30 days game time, skill training for multiple characters, or attire and special items through the Aurum store. In short, it's a way of converting real money to in-game ISK - or converting ISK to game time.
The economy of EVE is one of the most unique parts of the game. The total sandbox theme extends to most economic activity in game. Almost all items are made, sold and used by players; in many ways it's a kind of anarcho-capitalist paradise. It's also so complicated that CCP hired an economist for several years to help them figure out how to make it function. That complexity is a key part of the game's fascination for me.
PLEX as often been used as an indicator of economic activity in EVE. It allows for a translation between ISK and real money - which is how last year's massive capital ship fight in nullsec was estimated to cost $330,000 USD.
Unfortunately, having a way to convert real money to ISK means people will seek to convert back the other way - this is called Real Money Trading (RMT), leads to distortion in the EVE market and gaming environment, and is policed by CCP. The more RMT is cracked down on, the better the market for PLEX gets.
The recent decision to ban ISboxer, a way users can pay an outside party for access to software which can automate commands so that one computer can run multiple accounts, might not strictly be an example of action against RMT. However, it has also lead to a lot of movement on prices of PLEX, as many who were formerly using the software to grind and buy PLEX have stopped doing so. The net result, in EVE's free market? Falling PLEX prices. Good times for me :)