"Probable impossibilities are to be preferred to improbable possibilities." [Aristotle]
Here I present some functions for random number generation.
I assume that Excel's © internal rand() function generates random numbers of sufficient quality (that is: randomness). You may want to substitute it. In this case search the web for alternatives.
Examples of simple distribution functions are presented here.
Cholesky - Generate correlated random numbers with a Cholesky decomposition.
Iman Conover - Generate correlated random numbers with worksheet functions or with VBA.
sbGrowthSeries - Generate a random data series with a given compoundgrowth rate and a given maximum relative change rate per step
PF_Allocate - Generate portfolio assets with a given sum and lower boundaries and upper boundaries
Random_Pick - Pick n random cells from selection
RndDecPlace - Create a random number between two borders with a given number of decimal places.
sbExactRandHistogram - Create a random distribution with exactly the requested frequency for given numbers (Largest Remainder method will be applied if that is not exactly possible to minimize the absolute error)
sbRandInt - Generate n non-repeating (or repeating up to r times) random integers between two given borders
sbRandSum1 - Generate n random numbers which sum up to 1
UniqRandInt - Generate n unique random integer numbers in a given range 1..m (m >= n) [provided just for historical purposes - I suggest to use sbRandInt now]