Are there any good resources for creating pi calculation programs?

I'm working on a benchmarking application (yes yes i know been done but its a project to help further my programming abilities.) And i would like to include pi calculation in the tests, however i have been unable to find good resources on creating algorithms for calculating it's value.

Well, I found a recursive arctan formula.
The General Formulae
We have just seen that there are infinitely many formulae for Pi using the Fibonacci numbers! They are:
Pi/4 = arctan(1)
= arctan(1/2) + arctan(1/3)
= arctan(1/2) + arctan(1/5) + arctan(1/8)
= arctan(1/2) + arctan(1/5) + arctan(1/13) + arctan(1/21)
= arctan(1/2) + arctan(1/5) + arctan(1/13) + arctan(1/34) + arctan(55)
=...
or, putting these in terms of the Fibonacci numbers:
Pi/4 = arctan(1/F1 )
= arctan(1/F3) + arctan(1/(F4)
= arctan(1/F3) + arctan(1/F5) + arctan(1/F6)
= arctan(1/F3) + arctan(1/F5) + arctan(1/F7) + arctan(1/F8)
= arctan(1/F3) + arctan(1/F5) + arctan(1/F7) + arctan(1/F9) + arctan(1/F10)
= ...

You can use an algorithm to continue this recursion until you achieve the accuracy you desire.