I was looking at the Vedic Maths tutorials last night, and the one i particulary liked was for doing two, (or even three digit), multiplication very quickly:
The sutra used here is Vertically and Crosswise:
To multiply two numbers think of them as set out as below, 21 x 26 =
2 1
| x |
2 6
---------
4 (14) 6
---------
Multiply your first column together to get the first part of the answer, i.e 2 x 2 = 4.
Then, multiply crosswise, i.e 2 x 6 and 1 x 2, and add these numbers together to get the middle term, i.e 12 + 2 = 14.
Then multiply the last column together to get the last part of the answer, i.e 1 x 6 = 6.
When you have a number of more than one digit, you carry over as you would in "normal" maths, so here, the 1 from the 14 is added to the 4 at the beginning to give 5
And so the answer in this case is 546.