Peter Philpott, in his “The Art of Wrist-Spin Bowling”, described the concept of a spinner going “around the loop” – keeping the finger movement constant, but rotating the wrist between successive deliveries, to change the direction of spin.
So, for a right-arm wrist spinner, you might start with a “big leggie”, releasing the ball with the seam pointing at gully, or even cover; then a “little leggie”, with the seam directed to first slip; the top spinner, with the seam straight down the wicket; the googly, with the wrist now turned even further round so that the seam is spun towards leg slip.
Shane Warne’s “slider” might be the delivery at the opposite end of the loop to the googly – still with the same finger movement as a regular leggie, but now with palm of the hand towards gully and the seam pointing towards leg slip but with the fingers spinning the ball back towards the bowler.
And if that sounds like a convoluted description, just imagine how it must be to bowl the delivery!
For the finger spinner, perhaps the loop from doosra, through top-spinner and on to the regular off-break could be continued on to include the “flipper”…and back to Saqlain’s teesra…perhaps.
The Teesra 
>I've blogged on this: http://the-doosra.blogspot.com/2010/11/going-round-loop-plus-gyro-ball.html Bruce Charlton