RM500 million? Ong Tee Keat isn't the first to file a defamation suit but half a billion ringgit, I think, is a record of sorts as far as politicians are concerned. Anwar Ibrahim has probably filed the most number of multi-million ringgit suits - against NST, Dr Mahathir and most recently Utusan Malaysia - but his cap is RM100 million.
Defamation/libel suits have become part and parcel of Malaysian life. In 2003, the Federal Court confirmed the decision to stop awarding mega damages for defamation suits, a moved welcomed by Lim Kit Siang, even though he was suing Utusan Malaysia for RM250 million for calling him "tidak patriotik" [read here].
Around the time, The Malay Mail was facing a suit for RM1.8 billion for defamation from a perbadanan called Nascom.
p.s. Hindraf's self-exiled leader Waythamoorthy is also suing DAP for defamation, here.