It has been a week since episode 1 came out, here are more short forms for you to get accustom with :P (some are US, some aren't):

• 1337 / leet / l33t
  Elite (best of the best; cool)


• FFS
  For F***'s Sake


• MIA
  Missing in action


• NBTD
  Nothing better to do


• TTYL
  Talk to you later


• WTB / WTS / WTT
  Want to buy / Want to sell / Want to trade (Widely used in online gaming transactions)

After playing Water Margin Online for awhile, here's a few I've learned from the game (implies to the game solely):

• BDH
  Black Dragon Helmet


• GBH
  Golden Boar Helmet


• GDH
  Golden Dragon Helmet


• RDH
  Red Dragon Helmet


• UT
  Utmost

These, however are some miscellaneous words that isn't a short form, neither is it an abbreviation but oftenly used by most IM specialists:

• Rawr
  An expression of strength, intelligence after being complimented


• W00t / Woot
  An expression of happiness (in games / chats)