Abbreviations that ought to exist

I tweet more often than I blog these days, and sometimes I wish there were more universally-understood abbreviations so I could type less and say more within the 140-character straitjacket.

These would be handy, for example:

• OOC: Out Of Curiosity
• OTP: On The Phone (I've been trying to bring this to IMing for years)
  
• NNTR: No Need To Reply (as brought to my attention by the Email Charter)
• TLFT: Too Long For Twitter