A 'doosra' is a delivery that an off-spinner bowls with an off spin action that spins from right to left. (This is different to a normal off spin delivery that spins left to right.)
A 'googly' is a delivery that a leg spinner bowls with a leg spin action that spins from left to right. A 'googly' is also referred to as a 'wrong'un'. (This is different to a normal leg spin delivery that spins right to left.)
Saqlain Mushtaq was the inventor of the 'doosra' and he bowled it quite well. Currently, Muttiah Muralidaran, Harbhajan Singh and Ajantha Mendis bowl it very well. The master of the Doosra is definitely Muttiah Muralidaran.
Shane Warne and Anil Kumble are one of best 'wrong-un' bowler ever.
